Pythagoras' Theorem & Trigonometry

🦉 Pythagoras' Theorem

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

🦉 Trigonometric Ratios

\tan\theta=\frac{\text{opposite}}{\text{adjacent}}

\cos\theta=\frac{\text{adjacent}}{\text{hypotenuse}}

\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}

TOA CAH SOH is applicable for only right-angled triangles

🦉 Obtuse Angles

\sin(180^\circ-\theta)=\sin\theta

\cos(180^\circ-\theta)=-\cos\theta

🦉 Sine Rule

\dfrac{a}{\sin A}=\dfrac{b}{\sin B}

🦉 Cosine Rule

c^2=a^2+b^2-2 ab \cos C

🦉 Area of Triangle

\text{Area of triangle}=\frac{1}{2}ab \sin C

🦉 Bearings

A bearing is a 3-digit positive number with units of degree to show direction clockwise from the north direction.