Question

what is the measure of the complementary angle to 0.8 radians? Give an exact answer

Answer 1

Complementary angles sum to 90 degrees, right?

So 0.8 radians is how many degrees? Or keeping this in radians, 0.8 plus what is \(\cfrac{\pi}{2}\), which is 90 degrees in radians?
$$
\cfrac{8}{10}+x=\cfrac{\pi}{2}
$$
Solve for x.

That's it!

Answer 2

x=-4/5+pi/2?

Answer 3

That's right!
$$
x=-\cfrac{4}{5}+\cfrac{\pi}{2}=-\cfrac{8}{10}+\cfrac{5\pi}{10}=\cfrac{5\pi-8}{10}
$$
Which is an exact answer.