If in a right-angled triangle ABC angles A and B are acute, then evaluate
1 + tanAtanB =
sec2A
Given, in a right-angled triangle ABC angles A and B are acute.
Hence, A + B = 90∘.
So, 1 + tan(90−B)tanB
= 1 + cotBtanB
We know 1tanB=cotB
= 1 + cot2B
= 1 + cot2(90−A)
= 1 + tan2A
= sec2A (sec2A−tan2A=1)