Question

Find value of tanπ8 in easy way

Answer 1

we know tht

tan a = 2 tan a/2 / 1 - tan sqyare a/2

putting a = pie/4, we get

tan pie/4 = 2 tan pie/8 / 1 - tan square pie/8

1 = 2 tan pie/8 / 1 - tan square pie/8 ---------------- 1

let tan pie/8 = x, thn frm (1) 2x/ 1 - x square = 1

2x = 1 - x square

x square + 2x - 1 = 0

x = -2 +- underroot 4 + 4/2

x = -2 +- 2 root2/2

x = -1 +- root2

Answer 2

the value of tanπ 8 is -1× -2 cos