Question

Help with precalc identity type question? Medal and fan

If sinx= -3/5 and x is in quadrant 3, then tan2x =
A. 24/7
B. 12/7
C. -12/7
D. -24/7

Through calculation, I came up with C. Is that correct?

Answer 1

@rishavraj

Answer 2

I was thinking 4 quadrant sorry. So it would be 12/7 yeah?

Answer 3

its the wrong reply

Answer 4

Hmm what do we want to use here?
Tangent Double Angle Identity I guess?

Answer 5

Yep, 2tanx/ 1-tan^2x

Answer 6

@seehearcreate i guess its wrong question..all bcoz if x lies in 3rd quadrant then sin and cos both are supposed to have negative value...but according to question x comes to be positive..its impossible

Answer 7

There's a triangle in the third quadrant.
Understand how to label your sides using Sin x? :o

Answer 8

its cos x comes to be +ve

Answer 9

Not quite....

Answer 10

@rishavraj , the question is asking for a completely different angle.
2x instead of x.

I think it's probably not impossible :o
Let's see how it works out.

Answer 11

\[\Large\rm \sin x=\frac{opposite}{hypotenuse}=-\frac{3}{5}\]

Answer 12

Tip: The hypotenuse should never be the `negative` side.
So put the negative with the 3.

Answer 13

Ohhh, yeah I knew that sorry, I thought you meant something else in regards to the triangle in the unit circle.

Answer 14

oh :3