Ab = 20 cm, m∠a = 30° , and $m∠c = 45° . express the number of centimeters in the length of bc in simplest radical form.

Using the Sine Rule:-

20 /sin 45 =  BC / sin 30

BC = 20 sin 30 / sin45

  = 20 * 1/2  /  1 / sqrt2
  = 20 * 1/2 * sqrt2
=  10 sqrt2   answer