Question 957238
I think you're saying,
{{{tan^2(theta)=21/20}}}
{{{sin^2(theta)/cos^2(theta)=21/20}}}
{{{sin^2(theta)=cos^2(theta)(21/20)}}}
.
.
.
{{{sin^2(theta)+cos^2(theta)=1}}}
{{{(21/20)cos^2(theta)+cos^2(theta)=1}}}
{{{cos^2(theta)(21/20+20/20)=1}}}
{{{cos^2(theta)(41/20)=1}}}
{{{cos^2(theta)=20/41}}}
So then,
{{{sin^2(theta)=(21/20)(20/41)}}}
{{{sin^2(theta)=21/41}}}