HEL PLEASE Julian wants to use a sheet of fiberboard 21 inches long to create a skateboard
ramp with a 24° angle of elevation from the ground. How high will the ramp
rise from the ground at its highest end? Round your answer to the nearest
tenth of an inch if necessary.

Step-by-step explanation:

Given sin 30° = 1/2, to check which of the statements is correct we will apply the Pythagoras theorem to a right angled triangle shown in the attachment.

using the SOH CAH TOA trig identity on the right angled triangle, ACD gotten from the equilateral triangle ABC;

From ΔACD, AD is the hypotenuse, DC is the opposite side to the angle 30° and AC is the adjacent.

From the diagram, sin30° = opp/hyp = DC/AD

sin30° = 1/2

Taking consideration of the acute angle 60°, the opposite side to the angle will be AC and the adjacent side will be CD.

According to CAH, cos 60° = adj/hyp = CD/AD

Given CD = 1 and AD = 2

cos60° = 1/2

This shows that sin30° = cos60° = 1/2

Note that ∠CDA and ∠DAC are angles complementary. Complementary angles are angles which have its sum to be 90°