Question 149423
{{{sin(70)*cos(40) - cos(70)*sin(40)}}} Start with the given expression.



{{{sin(70-40)}}} Rewrite the expression using the identity {{{sin(x)*cos(y) - cos(x)*sin(y)=sin(x-y)}}}



{{{sin(30)}}} Subtract



{{{1/2}}} Take the sine of 30 to get 1/2



So {{{sin(70)*cos(40) - cos(70)*sin(40)=1/2}}}