Question

Thao sees a plane directly above her which is flying at a height of 800m. The plane continues flying at that height and 20 second later the angle of elevation of the plane from Thao is 35°.

a) How far did the plane travel in 20 seconds, correct to the nearest metre?
b) What is the plane's speed in km/h, correct to the nearest km

Answer 1

a. 1142.5 m

b. 57.13 m/s

Explanation:

a here we shall use the trigonometry to solve.

since the plane si moving it is covering some distance, we use the angle of elevation and the height from the ground to calculate the distance covered.

we use tan a = opposite/adjacent

tan 35 = 800/X

Xtan 35° = 800

X = 1142.5 m

b. speed = distance covered/ time taken

= 1142.5/20

= 57.125 m/s

= 57.13m/s