If f(x)=x^2-81 and g(x)=(x-9)^-1 (x+9) find g(x) x f(x)

F(x)=x^2-81
g(x)=((x-9)^-1)(x+9)
f(x)*(g(x))
(x^2-81)((x+9)/(x-9))
((x+9)(x-9))((x+9)/(x-9))
(x+9)(x+9)
x^2+9x+9x+81
x^2+18x+81

We are given with the length of the kite string of 80 meters and an angle of 75 degrees of the string with the ground. In this situation, the kite string is the hypotheneuse of the triangle and 75 degrees is the angle of elevation. The height of the kite from the ground is 80 sin 75  or 77.27 meters.