Answer:
23 m
Step-by-step explanation:
The computation of the height of the entire screen is shown below;
= a + b
where
a = 21 × tan 17 degrees
= 21 × 0.305
= 6.4 m
And
b = 21 × tan 38 degree
= 21 × 0.781
= 16.4 m
So, the height of the entire screen is
= 6.4 m + 16.4 m
= 22.8 m
= 23 m