Trigonometry-1

The hypotenuse of a right-angled triangle is 30 cm and one of the sides is 18 cm.

Find the third side and the sine, cosine and the tangent of the angle

opposite to the third side.

Solution: BC² = AC² - AB² = 30² - 18²

BC² = (30 + 18)(30 - 18)

i.e. BC² = 48 X 12

i.e. BC² = 16 X 36

Therefore, BC = 4 X 6 = 24 cm.

Therefore, Sin Θ = 24/30 = 4/5

Cos Θ = 18/30 = 3/5

Tan Θ = 24/18 = 4/3