Question

Please explain your process: http://prntscr.com/47nn8b

Answer 1

tan (7π/8) = tan (7π/4 /2). So we use the half angle formula for tangent, which is:
tan A/2 = sin A / (1+cosA)
tan (7π/4 /2) = (sin 7π/4) / (1+cos 7π/4)
= -√2/2 / (1+√2/2)
= -√2 / (2 + √2)
= -√2 (2-√2) / 2
= (2 - 2√2) / 2
= 1 - √2

Answer 2

thanks

Answer 3

no problem