Geometry — Concepts, Formulas, Shapes & Topics Guide
Geometry is the branch of mathematics that studies points, lines, angles, shapes, and space — how figures are built, measured, and related. This hub maps every geometry topic into ten clusters: foundations (points, lines, planes), angles, parallel lines and transversals, triangles, quadrilaterals and polygons, circles, 3D solids, coordinate geometry, conic sections, and transformations — each linking to a full guide with formulas and worked examples.
Sep 10, 2026#Geometry
Cos 5 Degrees: Value, Radians & How To Find It
Cos 5 degrees equals 0.9962 to four decimal places (more precisely 0.996195), where the angle in radians is (π)/36 ≈ 0.0873. There is no clean surd form the way cos 30^° = (√3)/2 has one, because 5^° is not a constructible angle; the honest tools are the decimal, the cofunction relation cos 5^° = sin 85^°, and a table, calculator, or power series. The angle sits in Quadrant I, so the value is positive.
Sep 10, 2026#Trigonometry
Cos 3 Degrees: Exact Value & Decimal
Cos 3 Degrees equals approximately 0.9986 (to four decimal places), and the angle in radians is (π)/60 ≈ 0.0524. A true exact surd form does exist, because 3^° = 18^° - 15^° and both of those are constructible, but it is a long nested radical that nobody uses in practice, so 0.9986 is the working value. Since 3^° sits in Quadrant I, the cosine is positive, and it is close to 1 because the angle is tiny.
Sep 10, 2026#Trigonometry
2sinAsinB Formula: Proof, Examples & Uses
The 2sinAsinB formula is a product-to-sum identity: 2sin Asin B = cos(A-B) - cos(A+B). It turns a product of two sines into a difference of two cosines, and it is the one product-to-sum rule that carries a minus sign. For a quick check, with A = 60^° and B = 30^° both sides equal (√3)/2 ≈ 0.8660.
Sep 10, 2026#Trigonometry
Roots In Polynomial Expressions: Full Guide
Roots in polynomial expressions are the values of x that make the polynomial equal zero, so a root of P(x) is any x with P(x) = 0. A number r is a root exactly when (x - r) is a factor, and by the Fundamental Theorem of Algebra a degree-n polynomial has exactly n roots when you count multiplicity and allow complex numbers.
Sep 10, 2026#Algebra
Zeros of a Quadratic Polynomial: Formula & Examples
The zeros of a quadratic polynomial are the input values that make it equal to zero, and a quadratic has at most two of them. You can find these zeros by factoring, by completing the square, or with the quadratic formula, and the discriminant b² - 4ac tells you in advance whether there are two, one, or no real zeros.
Sep 10, 2026#Algebra
Vector Algebra: Formulas, Operations & Examples
Vector algebra is the arithmetic of quantities that carry both size and direction: adding and subtracting vectors, scaling them by a number, and multiplying them in two distinct ways. The dot product a·b=|a||b|cosθ returns a scalar and measures how much two vectors point the same way; the cross product a×b=|a||b|sinθ,n returns a new vector at right angles to both.
Sep 10, 2026#Algebra
Variables Constants And Expressions: A Beginner Guide
Variables Constants And Expressions are the three first building blocks of algebra: a variable is a letter that stands for a changing or unknown value, a constant is a number that stays fixed, and an algebraic expression is what you build when you combine them with operations. Spot each one on sight, and the rest of algebra stops reading like a foreign language.
Sep 10, 2026#Algebra
Variable Expressions: Evaluate, Simplify & Examples
A variable expression is a combination of numbers, variables, and operation signs that stands for a value but has no equals sign. You work with it in two main ways: evaluate it by substituting a number for the variable, and simplify it by combining like terms. The single feature that separates a variable expression from an equation is that an expression is never "solved," only rewritten or measured.
Sep 10, 2026#Algebra
Value Of A Polynomial: How To Evaluate P(x)
The value of a polynomial P(x) at x = a is the number you get by substituting a for every x and simplifying, written P(a). Follow the order of operations carefully, especially with negative and fractional inputs, and remember one shortcut: P(a) is also the remainder when P(x) is divided by (x - a).
Sep 10, 2026#Algebra
Transitive Relations: Definition, Examples & Rules
A transitive relation is one where a link from a to b and a link from b to c force a link from a to c. The equals sign, "less than," and "is an ancestor of" all pass this test, while "is a friend of" fails it. Transitivity is one of the three properties, alongside reflexive and symmetric, that together build an equivalence relation.
Sep 10, 2026#Algebra
Types Of Matrices: List, Definitions & Examples
The types of matrices are the named categories a matrix belongs to based on its shape (row, column, square, rectangular), its entries (diagonal, scalar, identity, zero, triangular), how it behaves under the transpose (symmetric, skew-symmetric), and how it multiplies or inverts (singular, non-singular, orthogonal, idempotent, nilpotent, involutory). Naming the type is a shortcut: it tells you what a matrix can and cannot do before you compute anything. The overlaps between types, such as identity being a special scalar, cause most of the confusion.
Sep 10, 2026#Algebra
Symmetric Relations: Definition, Formula & Examples
A symmetric relation is a relation R on a set where every pair works both ways: if (a, b) belongs to R, then (b, a) must belong to R as well. Equality, "is a sibling of", and "is parallel to" are symmetric; "is less than or equal to" and "divides" are not. On a set of n elements there are 2 n(n+1)/2 symmetric relations, and symmetry is one of the three properties that build an equivalence relation.
Sep 10, 2026#Algebra
Sum And Product Of Zeros Of A Quadratic Polynomial
The sum and product of zeros of a quadratic polynomial are two formulas that tie a quadratic to its zeros. For ax² + bx + c with a ≠ 0 and zeros α and β, the sum of the zeros is α + β = -b/a and the product of the zeros is αβ = c/a. Reverse the two formulas and you can build a quadratic straight from its zeros: x² - (α+β)x + αβ. This single pair of relations lets you check zeros, form polynomials, and read a quadratic without solving it.
Sep 10, 2026#Algebra
Sum And Product Of Roots: Theory & Proof
The sum and product of roots theory says that for ax² + bx + c = 0 the two roots add to -b/a and multiply to c/a, so the coefficients already carry the answer before you solve. This article proves both results two ways, from the factored form and from the quadratic formula, then extends the pattern to cubics and to Vieta's formulas for any degree.
Sep 10, 2026#Algebra
Sum and Product of Roots: Formulas and Examples
The sum and product of roots let you read a quadratic's two roots straight from its coefficients: for ax² + bx + c = 0, the sum of the roots is -b/a and the product is c/a. That one idea builds an equation from its roots, checks answers without solving, and extends to cubics. The examples below work through each case step by step.
Sep 10, 2026#Algebra
Solving Quadratic Equations: 4 Methods & Examples
Solving quadratic equations means finding the values of x that make a second-degree equation equal to zero, and there are four reliable methods: factoring, completing the square, the quadratic formula, and graphing. Pick the method that fits the equation in front of you, then read the discriminant to know how many real roots to expect before you start.
Sep 10, 2026#Algebra
Sridharacharya Formula: Derivation & Examples
The Sridharacharya formula is the rule that solves any quadratic equation ax² + bx + c = 0, and it reads x = (-b ± √(b² - 4ac))/2a. It is the same result the rest of the world calls the quadratic formula, named for the Indian mathematician Sridharacharya, who gave the completing-the-square method behind it. The part under the square root, b² - 4ac, is the discriminant, and its sign tells you how many real roots the equation has before you solve.
Sep 10, 2026#Algebra
Special Cases In Linear Equations Explained
The special cases in linear equations are the three outcomes you can reach when you solve one: exactly one solution, no solution, or infinitely many solutions. When the variable survives, you get a single value like x = 4; when it cancels and leaves a false statement such as 0 = 5, there is no solution; when it cancels and leaves a true statement such as 0 = 0, every number works. For a pair of equations, the same three cases appear as lines that cross once, run parallel, or lie on top of each other.
Sep 10, 2026#Algebra
Subtracting Fractions With Unlike Denominators
Subtracting fractions with unlike denominators takes four steps: find the least common denominator (LCD), rewrite each fraction as an equivalent fraction over that denominator, subtract the numerators, and simplify. The denominators are never subtracted, they only tell you the size of the pieces you are working with.
Sep 10, 2026#Algebra