Setting up the right triangles

I would like to get some help setting up the right triangles so that I can solve this problem. The dimension of A is 4.75. Please see the attached file for full problem description.

Setting up trig problem

I would like to get some help in setting up this problem. I tried using the radius of the circle as one side of the triangle but have not been able to get the answer Please see the attached file for full problem description.

Phase angle

Phase angle 15.18 degrees. What is this value in radians?

length of a arc

Two people 1.8m tall walk from each other until they can no longer see each other (due to the curvature of the earth which has a radius of 6378km). Assuming nothing else blocks their view, how far do they have to walk? Note. I cant get my head around how this relates to what we've lear ...continues

Using triangle ABC, show that the form (cos(A/2))^x is able to find side lengths.

Let ABC be a triangle. Prove that (cos(A/2))^x, (cos(B/2))^x, and (cos(C/2))^x are the lengths of a triangle for any x greater than or equal to 0. From what I have found in my books, it is impossible to solve for side lengths of a triangle using AAA b/c there is no formula to do so. It is possible to find similar triangles ...continues

Prove or disprove identity

3sin(Theta)-4cos(Theta)=5sin(Theta + cos^-1[3/5])

Prove or disprove an identity

sec^2(X)csc^2(X)=sec^2(X)+csc^2(X)

Prove or disprove an identity

sec(X)/tan(X)+cot(X)=sin(X)

Prove a Trigonometric Identity

2tan(X)/1+tan^2(X)=sin2(X)

Solve conditional trigonometric equation (between 0 and 360)

cos2(Theta)-2sin^2(Theta)=-2