Question

please help me it's urgent.....​

Answer 1

since we know that (1+ tan²∆) = sec²∆

and cos(90°-∆) = sin∆

also cot(90°-∆) = tan∆

now putting values.

LHS

sec²∆×cos∆×sin∆

1/ cos²∆ × cos∆×sin∆

sin∆\cos∆

tan∆ ---------(1)

Now RHS

tan∆ ----------(2)

from 1&2

LHS=RHS

#proved!