Answer:
8.6
Step-by-step explanation:
Sine is opposite/hypotenuse so you have
Sin20° = a/25.
To get a you have to multiply 25 to both sides of the equation to get
25 Sin20° = a
Find Sin20° on a calculator and you'll get approximately 0.3420
Then you multiply Sin20° by 25 and you'll get approximately 8.5505 which rounds to 8.6 which is a.