# If cos x = sin(20 + x)° and 0° < x < 90°, then Value of x is °.

We will be using trigonometric identity to solve this.

## Answer: If cos x = sin(20 + x)° and 0° < x < 90°, then Value of x is 35°.

Let's solve this step by step.

**Explanation:**

Given that, cos x = sin(20 + x)° and 0° < x < 90°

We know that sine and cosine are co-functions, which means cos x = sin (90^{°} - x)

Given that, cos x = sin(20 + x)°

cos x = cos [90 - (20 + x)]°

cos x = cos (90 - 20 - x)°

cos x = cos (70 - x)°

Therefore, x = 70 - x

2x = 70

x = 35°