Trigonometric ratios

In a right-angled triangle, label the sides relative to angle θ:

• Hypotenuse (H): the longest side, opposite the right angle.
• Opposite (O): the side opposite θ.
• Adjacent (A): the side next to θ (not the hypotenuse).

SOH CAH TOA

• sin θ = O/H
• cos θ = A/H
• tan θ = O/A

Finding a side

A ladder 10 m long makes an angle of 60° with the ground. How high up the wall does it reach?