Please help!!!)
posted by Bryan .
If sin(x) = /45 and cos(y) = 5/13 with both x and y terminating in quadrant 1 find the exact value of cos(xy)
cos(4/5  5/13)
Is this what I would do?

I've never heard of a School Subject called "Please help!!!"
Please type your subject in the School Subject box. Any other words, including obscure abbreviations, are likely to delay responses from a teacher who knows that subject well.