Question #d989d
2 Answers
Jan 3, 2018
Explanation:
#"using the "color(blue)"trigonometric identity"#
#•color(white)(x)sin^2x+cos^2x=1#
#rArrcosx=+-sqrt(1-sin^2x)#
#"since "cotA>0" and "sinA>0#
#"then A is in the first quadrant where cos is positive"#
#cosA=sqrt(1-(15/17)^2)#
#color(white)(cosA)=sqrt(1-225/289)=sqrt(64/289)=8/17#
Jan 4, 2018
Explanation:
With
Now we can substitute: