Help me please. This is my last question

Answer: D. 44
Step-by-step explanation:
Here, we need to know the concept of trigonometry.
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Given
- The adjacent side of angle x and the hypotenuse.
- We are going to use Cosine.
Solve
cos (x) = 15/21
x = cos⁻¹ (15/21)
x ≈ 44
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