Verified answer

Answer:

The measure of obtuse angle is 114.77°

Step-by-step explanation:

Suppose ∠B is the obtuse angle.

Formula :

AC² = AB² + CB² - 2 × AB × CB × Cos ∠B

When using Cosine Law,

• 38² = 25² + 20² - 2 × 25 × 20 × Cos ∠B
• 1000 Cos ∠B = - 419
• Cos ∠B = - 0.419
• ∠B = Cos^-1(- 0.419)
• 114.77°