If #cos theta=-3/4# and tan theta is negative, how do you find the value of sin theta?
1 Answer
Mar 27, 2018
Explanation:
#"given "costheta<0rArr"second/third quadrant"#
#"given "tantheta<0rArr" second/fourth quadrant"#
#rArrtheta" is in second quadrant where "sintheta>0#
#•color(white)(x)sin^2theta+cos^2theta=1#
#rArrsintheta=+-sqrt(1-cos^2theta)#
#"since "sintheta>0" then"#
#sintheta=sqrt(1-(-3/4)^2)#
#color(white)(sintheta)=sqrt(1-9/16)=sqrt(7/16)#
#rArrsintheta=sqrt7/4#
