Trigonometric EquationHard
Question
If sin x + sin2 x = 1, then cos12x + 3cos10 x + 3cos8x + cos6x - 2 is equals to -
Options
A.0
B.1
C.-1
D.2
Solution
sin x = 1 - sin2x = cos2x
⇒ Now sin6x + 3sin5x + 3sin4x + sin3x - 2
= (sin2x)3 + 3(sin2x)2 sinx + 3(sin2x)2 + sin2x sinx -2
= (sin2x + sinx)3 -2 = 1 -2 = -1
⇒ Now sin6x + 3sin5x + 3sin4x + sin3x - 2
= (sin2x)3 + 3(sin2x)2 sinx + 3(sin2x)2 + sin2x sinx -2
= (sin2x + sinx)3 -2 = 1 -2 = -1
Create a free account to view solution
View Solution FreeMore Trigonometric Equation Questions
If tan θ - √2 sec θ = √3, then the general solution of θ -...Let A and B denote the statements A : cosα + cosβ + cosγ = 0 B : sinα + sinβ + sinγ = 0 If...The sign of the product sin 2 sin 3 sin 5 is -...cot θ = sin 2θ (where θ ≠ nπ, n is an integer ) then θ =...The minimum value of sin θ + √3 cos θ is -...