If sin θ = 21 over 29, use the Pythagorean identity to find cos θ.

Solution:

Given, sin θ = 21/29

We have to find cos θ

By pythagoras theorem,

a² + b² = c²

(21)² + b² = (29)²

441 + b² = 841

b² = 841 - 441

b² = 400

Taking square root,

b = 20

Sin θ = opposite/hypotenuse = 21/29

So, cos θ = adjacent/hypotenuse

= 20/29

Therefore, cos θ = 20/29

If sin θ = 21 over 29, use the Pythagorean identity to find cos θ.

Summary:

If sin θ = 21 over 29, using the Pythagorean identity cos θ = 20/29.