OH, thanks, i thought they had to have a difference of 11, which is what was confusing me
Oh, I figred it out... I just made a simple mistake...
80 degrees
Those are supplementary angles which means that their combined total is equal to 180 degrees.
180-100 is 80
so the answer is 80 degrees
why do you need to use law of cosines?
The triangle is a right triangle, so can´t you use the normal cos(A)= adjacent over hypotenuse