Question 682759
{{{highlight(cos(a+b)=cos(a)cos(b)-sin(a)sin(b))}}}
{{{cos(30+45)=cos(30)cos(45)-sin(30)sin(45)}}}
Use your unit circle or 45,45,90 and 30,60,90 triangles to evaluate:
{{{cos(30+45)=(sqrt(3)/2)(sqrt(2)/2)-(1/2)(sqrt(2)/2)}}}
Simplify:
{{{highlight(cos(30+45)=(sqrt(6)-sqrt(2))/4)}}}