Question

.......... solve .......

Answer 1

since we know that cosX = sin(90-X)

so we can write cos20 as sin(90-20) = sin20

so sin70 / cos20 = sin70 / sin70 = 1

similarly for tan i.e tan15 = cot 15

i.e tan35 = tan 15

so on solving it we get

11/7 - 4/7 = 1 is the answer