SOLUTION: A radio tower 138 m tall is supported by a guy wire which makes an angle of 71° with the ground. The company maintaining the tower wishes to move the base of the guy wire an additi

Algebra ->  Trigonometry-basics -> SOLUTION: A radio tower 138 m tall is supported by a guy wire which makes an angle of 71° with the ground. The company maintaining the tower wishes to move the base of the guy wire an additi      Log On


   



Question 1110131: A radio tower 138 m tall is supported by a guy wire which makes an angle of 71° with the ground. The company maintaining the tower wishes to move the base of the guy wire an additional 8 m from the base of the pole.
a) How much additional wire will be needed?
b) What angle will the new wire make with the ground?
Thank you so much :)

Answer by josgarithmetic(39621) About Me  (Show Source):
You can put this solution on YOUR website!

First part of drawing a figure:
Right triangle, height 138, base length x, hypotenuse, r.
x is how far the ground attachment of the guy wire;
71 degrees where guy wire is attached to the ground;
r, the original wire length from top of tower to attachment point on ground at x away from tower base.

138%2Fr=sin%2871%29
r%2F138=1%2Fsin%2871%29
r=138%2Fsin%2871%29
-
cos%2871%29=x%2Fr
x=r%2Acos%2871%29
x=138%28cos%2871%29%2Fsin%2871%29%29


Next triangle, also right triangle,
leg vertical of 138,
horizontal leg of x+8, and you can now evaluate this leg;
R, the longer hypotenuse than was r;

Again, you now should have the value of x:
%28x%2B8%29%5E2%2B138%5E2=R%5E2
and with this you should be able to find R.

First question asks for difference between R and r.