Question

without using trigonometric tables find the value of the following ​

Answer 1

(tan20/cosec70)^2+(cot20/sec70)^2+2tan15.tan45.tan75

(tan20/sec20)^2+(cot20/cosec20)^2+2.tan15.cot15

(sin20)^2+(cos20)^2+2

1+2

=3