Question

From a point A on ground level, the angle of elevation to a plane is 75 degrees. From a point B on the ground, due west of A, the angle of elevation is 47 degrees. If A and B are 3500m apart, find the height of the plane off the ground.

Answer 1

Start by drawing a diagram, similar to the one attached.

Call G the point at the ground directly below P.
Internal angle at A (a) = 180 - 75 = 105 degrees
Internal angle at B (b) = 47 degrees
Internal angle at P (p) = 180 - 105 - 47 = 28 degrees

AB/sin(p) = AP/sin(b)
3500/sin(28) = AP/sin(47)
AP = (3500/sin(28)) * sin(47)

PG/sin(75) = AP/sin(90)

PG = (AP/sin(90)) * sin(75)

Make sense?

Answer 2

okay that makes sense, Thankyou!

Answer 3

No worries =)