Question 78644
It helps to draw a picture of the situation:
The 35-ft. mast forms the upright leg of a right triangle while the 20-ft. shadow forms the base of the same right triangle.
The angle of elevation of the sun is the angle between the base (shadow) and the hypotenuse of this right triangle. Let's call this angle A.
Now, since you know the length of the side opposite angle A (35 ft.) and the length of the side adjacent to angle A (20 ft.), you can use the Tangent function to find the measure of angle A.
Recall the acronym:
SohCahToa (o:opposite side, a:adjacent side, h:hypotenuse)
Sin = o/h
Cosine = a/h
Tangent = o/a
So, you can write:
{{{Tan(A) = 35/20}}}
But you really want the angle (A) whose tangent is 35/20, so
{{{A = Tan^(-1)(35/20)}}} This is known as the Arctangent and you should have this key on your calculator. If not, use INV TAN
{{{A = 60.255}}}degrees.