Right-angled trigonometry · Year 9

In Year 9 you learn: sine, cosine and tangent in right-angled triangles.

Trigonometry links the angles and sides of right-angled triangles. Label the sides from the angle you are using (opposite, adjacent, hypotenuse), choose sin, cos or tan with SOH CAH TOA, and you can find any missing side or angle.

Key facts

• SOH: sin θ = opposite ÷ hypotenuse.
• CAH: cos θ = adjacent ÷ hypotenuse.
• TOA: tan θ = opposite ÷ adjacent.

Other years

• Right-angled trigonometry · Year 10
• Right-angled trigonometry · Year 11