sin=opositeside/hyptonuse
cos=adjacentside/hyptoonse
try and draw a diagram
pretend we gots
acute angle is on left side
right angle is below obtuse angle
so sinA=7/25=left side/hypotonuse
so we need to find other side
pythagorean theorme
a²+b²=c²
7²+b²=25²
49+b²=625
b²=576
b=24
so
sinA=o/h
cosA=a/h
7=o
25=h
24=a
cosA=24/25
