Question

Can someone please please please help? I'm so confused. I've been on this problem for an hour.

Answer 1

$\cos(A-B)=\cos A\cdot\cos B+\sin A\cdot\sin B=\dfrac{35}{37}\cdot\dfrac{21}{29}+\dfrac{12}{37}\cdot\dfrac{20}{29}=\\\\\\=\dfrac{735}{1073}+\dfrac{240}{1073}=\dfrac{975}{1073}\approx0.91$