Please help me (It's for a really important grade)

Answer:
4/5
Step-by-step explanation:
Sin = Opposite / Hypotenuse
Note that hypotenuse = longest side
We want to find sinФ
The opposite side length of angle "Ф" has a length of 8 and the longest side or hypotenuse has a length of 10
So sinФ would equal 8/10 which can be simplified to 4/5