Posted by **B.S.** on Friday, June 12, 2009 at 1:00am.

The expression 4 sin x cos x is equivalent to which of the following?

(Note: sin (x+y) = sin x cos y + cos x sin y)

F. 2 sin 2x

G. 2 cos 2x

H. 2 sin 4x

J. 8 sin 2x

K. 8 cos 2x

Can someone please explain how to do this problem to me?

- trig -
**Quidditch**, Friday, June 12, 2009 at 2:50am
Given:

sin(x+y)=sin(x)cos(y) + cos(x)sin(y)

For the case y=x:

sin(x+x) = sin(x)cos(x) + cos(x)sin(x)

=sin(2x) = 2sin(x)cos(x)

or, just to make it easier

2sin(x)cos(x) = sin(2x)

so, what does 4sin(x)cos(x) = ?

## Answer This Question

## Related Questions

- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- tigonometry - expres the following as sums and differences of sines or cosines ...
- trig - Reduce the following to the sine or cosine of one angle: (i) sin145*cos75...
- algebra - Can someone please help me do this problem? That would be great! ...
- Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...
- Trig - Find sin(s+t) and (s-t) if cos(s)= 1/5 and sin(t) = 3/5 and s and t are ...
- Precal - I do not understand how to do this problem ((sin^3 A + cos^3 A)/(sin A...
- Trig - Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 < v < ...
- Calculus 12th grade (double check my work please) - 1.)Find dy/dx when y= Ln (...
- trig - it says to verify the following identity, working only on one side: cotx+...

More Related Questions