Question 832332
{{{cos^2(theta)+sin^2(theta)=1}}}
{{{cos^2(theta)+(2/5)^2=1}}}
{{{cos^2(theta)=1-4/25}}}
{{{cos^2(theta)=21/25}}}
{{{cos(theta)=sqrt(21/25)}}}
{{{tan(theta)=2/sqrt(21)=(2*sqrt(21))/21}}}