Class 7 — Maths Formula Sheet

(+a) + (+b) = +(a+b)
(−a) + (−b) = −(a+b)
(+a) + (−b) = a−b (if a>b)

Rules for adding positive and negative integers.

(+) × (+) = (+)
(−) × (−) = (+)
(+) × (−) = (−)

Sign rules for multiplication of integers.

p/q where p, q ∈ ℤ and q ≠ 0

A number expressible as a ratio of two integers.

ax + b = c  →  x = (c − b) / a

Isolate x by moving constants and dividing by coefficient.

💡 2x + 3 = 9 → x = 3

∠A + ∠B = 90°

Two angles that add up to 90°.

∠A + ∠B = 180°

Two angles that add up to 180°.

∠A = ∠C,  ∠B = ∠D

Opposite angles formed by two intersecting lines are equal.

∠A + ∠B + ∠C = 180°

Sum of all interior angles of a triangle is 180°.

Exterior ∠ = sum of two non-adjacent interior angles

An exterior angle equals the sum of the two opposite interior angles.

C = 2πr = πd

Distance around a circle.

📌 r = radius, d = diameter

A = πr²

Area enclosed by a circle.

📌 r = radius, π ≈ 3.14159