Question

tan theta=3/8 third quadrant,find cos theta

Answer 1

\[\sec ^{2}\theta-\tan ^{2}\theta=1,\sec ^{2}\theta=1+\tan ^{2}\theta=1+\frac{ 9 }{ 64 }=\frac{ 73 }{64 }\]
\[\cos ^{2}\theta=\frac{ 64 }{73 },\cos \theta=\frac{- 8 }{\sqrt{73} }\]

Answer 2

Thanks!

Answer 3

yw