Question

If cosx = -1/2 and x lies in 3 quadrant find sin x​

Answer 1

Step-by-step explanation:

Cosx = -1/2

Cosx = Cos(-60)

x lies in the 3rd quadrant .

So ,

Cosx = Cos(π + 60)

Cosx = Cos(180 + 60)

Cosx = Cos 240

x = 240

Now ,

Sinx

=> Sin240

=> Sin(180 + 60)

=> Sin(-60)

=> -Sin 60

=>$\small \bold{-\dfrac{\sqrt{3}}{2}}$

Answer 2

Step-by-step explanation:

COS X=-1/2 IF 'X' LIES IN 3 rd QUADRANT IN 3 QUADRANT ONLY TAN AND COT ARE POSITIVE REMAINING ARE NEGATIVE

COS X=-1/2*-[MULTIPLYING BY MINUS BECAUSE TO GET 1/2 AS POSITIVE THEN WE CAN KNOW THE THETHA VALUE]

COSX=-1/2*-

COS X=1/2 WE GET 1/2 IN COS .WE GET  COS 1/2 AT COS 60 DEGREES

SO,SIN60=ROOT3/2 AND IT LIES IN 3 QUADRANT SIN 60 IS   NEGATIVE

SO,SINX=- ROOT3/2

HERE X MEANS 60