Answer:
a = 17 sqrt(2)
Explanation:
Since this is a right triangle, we can use trig functions
sin theta = opposite / hypotenuse
sin 45 = 17/a
Multiply each side by a
a sin 45 = 17
Divide each side by sin 45
a = 17 / sin 45
a = 17 / ( 1 / sqrt(2))
a = 17 sqrt(2)