Theorems (Junior Cert Mathematics): Flashcards

Always equal when two lines cross

Angles opposite equal sides are equal

Equal on opposite sides of crossing line

$180°$

Equal in same position on each line

Sum of two opposite interior angles

Opposite sides equal length, opposite angles equal

Bisect each other (cut in half)

Equal segments on one = equal on any other

Parallel line divides sides into equal ratios

Proportional (in same ratio)

$c^2 = a^2 + b^2$ (c is hypotenuse)

$\frac{base \times height}{2}$

Diagonal divides into two equal areas

Twice the angle at edge (same arc)