Question

How do you do this problem?

Answer 1

Answer: 135 and 45

Explanation:

We can read off from these equations the gradients of the two lines: (3) and (-2).

Then we quote the trigonometric identity tan(A-B) = [tan(A)-tan(B)] / [1+tan(A)tan(B)]

Substituting tan(A)=3 and tan(B)=-2 gives tan(A-B) = [(3)-(-2)] / [1+(3)(-2)] = 5/-5 = -1

So A-B = 135°.

That is the obtuse angle between the two lines, so the acute angle is 45°.