The given triangle is a right angle triangle. Taking angle C as the reference angle,
hypotenuse = AC = 20
opposite side = AB = x
We would find x by applying the Sine trignometric ratio which is expressed as
Sin# = opposite side/hypotenuse
Thus,
Sin 35 = x/20
x = 20Sin35
x = 20 * 0.574
x = 11.48
Rounding to the nearest tenth,
x = 11.5
