Vertices a and b of triangle abc are on one bank of a river, and vertex c is on the opposite bank. the distance between a and b is 200 feet. angle a has a measure of 33°, and angle b has a measure of 63°. find b.

A suitable solver will tell you instantly that the measure of b is 179.18 ft.

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If you want to do it yourself (meaning also with the aid of a calculator), you can use the Law of Sines. The given side is side "c", so you need the measure of angle C. That will be
  180° -33° -63° = 84°
Then side "b" can be found from
  b/sin(B) = c/sin(C)
  b = c*sin(B)/sin(C)
  b = (200 ft)*sin(63°)/sin(84°) ≈ 179.183 ft