Question 1080540
You know that,
{{{sin^2(theta)+cos^2(theta)=1}}}
{{{sin^2(theta)+(6/7)^2=1}}}
{{{sin^2(theta)+(36/49)=1}}}
{{{sin^2(theta)=49/49-36/49}}}
{{{sin^2(theta)=13/49}}}
{{{sin(theta)=0 +- sqrt(13)/7}}}