Answer:
[tex] 38^\circ [/tex]
Step-by-step explanation:
We assume that the ground is horizontal and the tower is vertical. The guy wire, the ground, and the tower form a right triangle. The guy wire is the hypotenuse. I'll call the angle formed by the guy wire and the ground angle A. For angle A, the tower is the opposite leg. Since we know the opposite leg and the hypotenuse, we use the sine ratio.
[tex] \sin A = \dfrac{opp}{hyp} [/tex]
[tex] \sin A = \dfrac{13~m}{21~m} [/tex]
To find the measure of angle A, we use the inverse sine function.
[tex] A = \sin^{-1} \dfrac{13}{21} [/tex]
[tex] A = \sin^{-1} 0.6190476 [/tex]
[tex] A = 38^\circ [/tex]