## sara1234 3 years ago Help please ?

1. soty2013

sure

2. anonymous

you are looking for the number between 0 and $$\pi$$ whose cosine is $$\frac{1}{2}$$

3. anonymous

if you still have that cheat sheet, look at the place on the upper half of the unit circle where the second coordinate is $$\frac{1}{2}$$

4. anonymous

5. Aperogalics

π/3 simple

6. Aperogalics

:)

7. anonymous

ok here is the picture |dw:1351127015253:dw|

8. anonymous

in this picture, $$\theta=\arctan(2)$$ an angle whose tangent is 2 since tangent is "opposite over adjacent" i labelled the opposite side 2 and the adjacent side 1

9. anonymous

the hypotenuse we find by pythagoras, it is $$\sqrt{1^2+2^2}=\sqrt{1+4}=\sqrt{5}$$

10. anonymous

and using sine as "opposite over hypotenuse" we see that the sine of the angle is $\frac{2}{\sqrt{5}}$