Question

Find the point on the terminal side of \(\theta~=~-\dfrac{3\pi}{4}\) that has an x coordinate of -1. Show your work.

Answer 1

@Callisto

Answer 2

What is \(\frac{3\pi}{4}\) in degrees?

Answer 3

\(\dfrac{3\pi}{4}*\dfrac{180}{\pi}=\dfrac{540\pi}{4\pi}\pi~cancels\\\dfrac{540}{4}=135\)

Answer 4

Yes. So, \(-\frac{3\pi}{4} \)=-135°
Can you locate where -135° is in this drawing?

Answer 5

Mark the x-coordinate.

Can you find the y-coordinate?

Answer 6

-1, -1?

Answer 7

Yes

Answer 8

how would I explain how I got the y? just say that I drew the line at -135 and looked at what y is when x is -1?

Answer 9

Have you learnt trigonometric ratios?

Answer 10

like sine, cosine, tangent, etc?

Answer 11

Yes

Answer 12

would tan(-135)=\(-\tfrac{y}{1}\) be correct?

Answer 13

\[\tan(-135) = \frac{y}{-1}\]

Answer 14

tan(-135)=1
1=y/-1
*-1
-1=y

Answer 15

y=-1
Make sure you have the unknown on the left of the equation.