Question

Given sinx=2/3 find cosx

Answer 1

`\cos\theta=(√(5))/(3)`

Explanation:

`\sin\theta=(2)/(3)\\ \\\cos\theta=(√(3^2-2^2))/(3)=(√(9-4))/(3)=(√(5))/(3)`

Construct a right triangle with hypotenuse 3 and opposite side 2. The adjacent side used for cosine can easily be calculated using the Pythagorean Theorem.