Cos^2 35-sin^2 35/ 2sin35cos35

Question

Cos^2 35-sin^2 35/ 2sin35cos35

Answer 1

Cos^2a - sin^2a = cos(2a)
2sinacosa = sin(2a)

cos(2*35)/sin(2*35) = cos70 /sin70 = ctg 70