Question

3sinx=4cosx find 4sin^2x - 3cos^2x +2​

Answer 1

Answer:

Step-by-step explanation:

3sinx+4cosx=5

=> 3/5 sinx +4/5 cosx = 1

let cosA=3/5 => sinA=4/5

=> cosAsinx + sinAcosx = 1

=> sin(x+A) = 1

Now,

4sinx - 3cosx

= 5(4/5sinx - 3/5 cosx) [multipying numerator and denominator by 5]

= 5(sinAsinx - cosAcosx)

= -5{cos(x+A)} = -5[root{1-(sin(x+A)^2)}] = -5 x 0 = 0 Ans: 0