Question 961016
If sin A= -1/squareroot of 5 with A in QII, find sin 2A
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{{{sinA=-1/sqrt(5)=-sqrt(5)/5}}}
{{{cosA=sqrt(1-sin^2(A))=sqrt(1-(1/5))=sqrt(4/5)=2/sqrt(5)=2sqrt(5)/5}}}
sin2A=2cosAsinA=2*√5/5*2√5/5=20/25=4/5