Step-by-step explanation:
for sin we divide the opposite by the hypotenuse
and for cos we require the adjacent divided by hypotenuse
we can get it through
a²+ b²=c²
ur unknown in this case is the adjustment which you can either substitute with a or b
a² + 3²=5²
a²=5²-3²
a²= 25-9
a²= 16

a=4
so that now we have found that I just sent we can find the cos of A
cos A= ⅘