Sunday

April 20, 2014

April 20, 2014

Posted by **mike** on Monday, April 6, 2009 at 3:46pm.

i'm not completely sure that this is right but i used the difference of two squares on it to get (sin(a)+cos(b))(sin(a)-cos(b)) then after that i am stuck. please help

- math -
**Reiny**, Monday, April 6, 2009 at 4:32pmIt will surprise you to see how easy this one is.

we know that sin^2 a + cos^2 a = 1

and sin^2 b + cos^2 b = 1

then

sin^2 a + cos^2 a = sin^2 b + cos^2 b

now let's "move" the terms cos^2 a and cos^2 b to get the needed equation

sin^2 a - cos^2 b = sin^2 b - cos^2 a

Done!

**Related Questions**

tigonometry - expres the following as sums and differences of sines or cosines ...

Math - Calculus - The identity below is significant because it relates 3 ...

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 - Reduce the following to the sine or cosine of one angle: (i) sin145*cos75...

TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...

math - Can you please check my work. A particle is moving with the given data. ...

Precal - I do not understand how to do this problem ((sin^3 A + cos^3 A)/(sin A...

math - Prove that for all real values of a, b, t (theta): (a * cos t + b * sin t...

MATH - Hi, I really need help with these questions. I did some of them halfway, ...