You should know these formulas by heart.

Some of these have different versions floating around.

I strongly recommend you use these versions.

**Areas of Shapes**

**Area of a Triangle**

$$ A = \frac{b × h}{2} $$

**Area of a Trapezium**

$$ A = \frac{a + b}{2} × h $$

**Area of a Circle**

$$ A = \pi r^2 $$

**Circumference of a Circle**

$$ C = \pi D $$

**Pythagoras’ Theorem**

$$ a^2 + b^2 = c^2 $$

**The Quadratic Formula**

$$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$$