Using Law of sines or Cosines

Side a measures 24 yd

Step-by-step explanation: Please refer to the attached diagram for details.

In this triangle as indicated by the details given, we have two sides measuring 12 and 21. Both sides do not have the corresponding angles given. Angle A measures 89° and the corresponding side is not given. We shall apply the Cosine Rule which states that;

a² = b² + c² - 2bcCosA

a² = (21² + 12²) - 2(21 x 12) x Cos89

a² = (441 + 144) - 2(252) x 0.0175

a² = 585 - (504 x 0.0175)

a² = 585 - 8.82

a² = 576.18

Add the square root sign to both sides of the equation

a = √576.18

a = 24.0037

Approximately, a = 24

-8

step-by-step explanation: