Question

y= Asinx+Bsin2x
curve passes through P(π/2, 3) and gradient at x=π/4 is 3 √(2) ÷ 2

Find A and B.

I found A as 3, but cannot find B, as it always gets multiplied by a sine or cos that is zero.

Answer 1

Answer:

A=3 & B=0

Step-by-step explanation:

y=Asin x+B sin2x , curve passes through the point p (pi/2,3).

3 =A sin pi/2+B sin pi

3=A.1+B.0=> A=3

dy/dx= A cos x+ 2B.cos 2x

(3×2^1/2)/2=A cospi/4 + 2 B cos pi/2 , put A=3

or 3/2^1/2=3.1/2^1/2+ 2B cos pi/2

or 0= 2Bcos pi/2 => B= 0

A=3 , B= 0 , answer.