A person 100 meters from the base of a tree, observes that the angle between the ground and the top of the tree is 18 degrees. Estimate the height h of the tree to the nearest tenth of a meter.

This is right angle trig. We know that ...

cos (18°) x hypotenuse = 100

hypotenuse = 100/cos (18°)

hypotenuse = 105.15 meters approx.

Because they want the height of the tree we want "sin (18°) x hypotenuse".

sin (18°) x 105.15 = 32.5 meters approx.

answer: 32.5 meters approx.