TRIGONOMETRY A2

Given that Sin Ө  = 4/9, Find Cos Ө.

Solution

Sin²Ө + Cos²Ө = 1

(4/9)² + Cos²Ө = 1

Cos²Ө = 1 - (4/9)²

Cos²Ө = 1 - ¹⁶/81

Cos²Ө =⁸¹/81 - ¹⁶/81

Cos²Ө = ⁶⁵/81

CosӨ =  √(⁶⁵/81)

CosӨ =  √65      answer

                9

TRY THIS………

Given that Sin Ө  = 3/8, Find Cos Ө.