Question

Question 17 Prove that [sin(5x) + sin(3x)] / [cos(5x) + cos(3x)] = tan(4x)

Class X1 - Maths -Trigonometric Functions Page 73

Answer 1

LHS = (sin5x + sin3x)/(cos5x + cos3x)
use the formula,
sinC + sinD = 2sin(C + D)/2.cos(C-D)/2
cosC + cosD = 2cos(C + D)/2.cos(C - D)/2

= {2sin(5x+3x)/2.cos(5x-3x)/2}/{2cos(5x+3x)/2.cos(5x-3x)/2}
= (2sin4x.cosx)/(2cos4x.cosx)
= sin4x/cos4x
= tan4x = RHS

Answer 2

Answer:

make me brilliant am a +1student