Posted by **Amy** on Saturday, March 19, 2011 at 10:00am.

the original problem was:

(sin x + cos x)^2 + (sin x - cos x)^2 = 2

steps too please

I got 1 for (sin x + cos x)^2

but then what does (sin x - cos x)^2 become since it's minus?

- Math -
**Reiny**, Saturday, March 19, 2011 at 12:07pm
see reply to your earlier post of this question

- Math -
**Anonymous**, Saturday, March 19, 2011 at 5:06pm
(a+b)^2=a^2+2*a*b+b^2

(a-b)^2=a^2-2*a*b+b^2

[sin(x)+cos(x)]^2=

[sin(x)]^2 +2*sin(x)*cos(x)+ [cos(x)]^2

[sin(x)-cos(x)]^2=

[sin(x)]^2 -2*sin(x)*cos(x)+ [cos(x)]^2

[sin(x)+cos (x)]^2+[sin(x)-cos (x)]^2=

[sin(x)]^2 +2*sin(x)*cos(x)+ [cos(x)]^2+

[sin(x)]^2 -2*sin(x)*cos(x)+ [cos(x)]^2=

+[cos(x)]^2+[cos(x)]^2+[sin(x)]^2+[cos(x)]^2=

2*[[sin(x)]^2+[cos(x)]^2]=2*1=2

Becouse: [sin(x)]^2+[cos(x)]^2=1

- Math -
**Anonymous**, Saturday, March 19, 2011 at 5:08pm
[sin(x)+cos(x)]^2=

[sin(x)]^2 +2*sin(x)*cos(x)+ cos(x)]^2

[sin(x)-cos(x)]^2=

[sin(x)]^2 -2*sin(x)*cos(x)+ cos(x)]^2

## Answer This Question

## Related Questions

- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- algebra - Can someone please help me do this problem? That would be great! ...
- Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...
- 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...
- 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 < ...
- Trig - Find sin(s+t) and (s-t) if cos(s)= 1/5 and sin(t) = 3/5 and s and t are ...
- trig - The expression 4 sin x cos x is equivalent to which of the following? (...
- Trigonometry - Solve the equation for solutions in the interval 0<=theta<...

More Related Questions