Question #88fc8

1 Answer
Somebody N.
Dec 20, 2017

#sintheta=(2sqrt(6))/5#

Explanation:

Identity:

#color(red)(sin^2x+cos^2x=1)#

#cos^2theta=(-1/5)^2=1/25#

#sin^2theta=1-cos^2theta#

#sin^2theta=1-1/25=24/25#

#sintheta=sqrt(24/25)=+-(2sqrt(6))/5#

For #pi/2< theta < pi#

#sintheta=(2sqrt(6))/5#

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