Posted by **katie** on Sunday, April 22, 2007 at 2:53pm.

Choose the two options which are true for all values of x

1) cos (x) = cos ( x – pie/2)

2) sin (x + pie/2) = cos (x – pie/2)

3) cos (x) = sin (x – pie/2)

4) sin (x) = sin (x + 4pie)

5) sin (x) = cos (x – pie/2)

6) sin^2 (x) + cos^2 (x) = pie

would it be 1 and 3 ??

I helps if you know the shape of the standard sine and cosine fucntion.

Also you will have to know that sin(x+A) is a horizonatal translation of A to the LEFT (obviously sin(x-A) would shift to the right)

if all else fails, pick any angle for x and realize that pi radians = 180º

lets check #3, let x= 37.6º (notice I don't pick a nice standard angle)

cos 37.6=.7922896

sin(37.6-180)=-.7922896 (opposites) so #3 is false

try the same angle in #5

## Answer This Question

## Related Questions

- maths - Choose three options which are true: a) an angle of 150 degrees is ...
- maths - Choose three options which are true: a) an angle of 150 degrees is ...
- Calculus grade 12 - solve for (<_ = less than or equal to / pie = pie sign...
- calculus - Hi i have two questions: what is the exact value of cos 5(pie)/12? ...
- math - evaluate the expressions below and leave them in radical form. 1. sin(pie...
- tigonometry - expres the following as sums and differences of sines or cosines ...
- maths - prove that sin sqared pie/6+ cos sqared pie/3-tansqare pie/4=1/2 in ...
- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...
- calculus - Differentiate. y= (cos x)^x u= cos x du= -sin x dx ln y = ln(cos x)^x...

More Related Questions