Question

Solve for theta, given sin theta + cos theta = 0
and 0<= theta <=pi

Answer 1

subtract the cos:
sin(theta)=-cos(theta)
Divide by cos(theta)
-tan(theta)=1
tan is one at pi/4.
Its negative in quadrant 2 so 3pi/4

Answer 2

so you can;t square it?

Answer 3

You mean try to do sin^2(theta)+cos^2(theta)=1 or square it to get rid of the negative 1?

Answer 4

yes first one

Answer 5

Well, if you square it you get (sin(x)+cos(x))^2=sin^2(x)+cos^2(x)+2sin(x)cos(x) So that doesn't quite help. You get 1+sin(2x)=0 (using the double angle formula sin(2x)=2sin(x)cos(x) Then you could subtract) 1=-sin(2x) Either way, you get the same answer :P

Answer 6

that makes sense - thank you!

Answer 7

No problem :D