Answer:
The height of the antenna is 7.0 m
Step-by-step explanation:
Let the height of the antenna be represented by x, and the distance from Avani's eyes to the top of the building A by y. And let z = x + y, so that:
Tan 42 = [tex]\frac{y}{21}[/tex]
y = Tan 42 x 21
= 0.9004 x 21
= 18.9084
y = 18.91 m
Also,
Tan 51 = [tex]\frac{z}{21}[/tex]
z = Tan 51 x 21
= 1.2349 x 21
= 25.9329
z = 25.93 m
Therefore,
x = z - y
= 25.93 - 18.91
= 7.02
x = 7.02 m
The height of the antenna is 7.0 m