Question

A plane takes off at an angle of elevation of 15 degrees and travels in a straight line for 3000 meters what is the height of the plane above the ground at this instant

Answer 1

You need to set up this equation into a triangle . 
The height of the plane above ground is 803.84 m/ft

When setting up the triangle remember the angle of elevation is in the bottom and then the bottom part of the triangle would be 3000 m since the plane travelled straight. and I used tan to help me solve this equation

Answer 2

sinα=height/hypotenuse

height=hypotenuse*sinα, 

We are given that hypotenuse is 3000m and α=15 so

h=3000sin15° m

h≈776.46 m  (to nearest hundredth of a meter or to the nearest centimeter)