help!!

cos = adjacent / hypotenuse         you will need to calculate the hypotenuse first ...using pythagorean theorem...

     what do you find for the hypotenuse length?

sin = opposite / hypotenuse

tan = opposite/adjacent

csc= 1/sin

AB  is the  hypotenuse=   sqrt  (8^2 + 4^2)   =  sqrt ( 64 + 16) =  sqrt (80)   =  sqrt (16 * 5)  = 4sqrt (5)

cos B  =  BC / AB =   4 / [ 4sqrt (5) ] =   1 / sqrt (5)   =    sqrt (5)   / 5

csc B =   AB / AC =  4sqrt (5) / 8   =   sqrt (5)  / 2

tan A =  BC / AC   = 4 / 8    = 1  / 2