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# 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

a^{2 }+ b^{2} = c^{2}

(21)^{2 }+ b^{2} = (29)^{2}

441 + b^{2} = 841

b^{2} = 841 - 441

b^{2 }= 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.

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