Determine the sine of the angle ABC.
Sin2ABC = 1 – Cos2ABC = 1 – (√7 / 4) 2 = 1 – 7/16 = 9/16
SinABS = 3/4.
Through the leg AC and the sine of the corner opposite to it, we determine the length of the hypotenuse AB.
SinABC = AC / AB.
AB = AC / SinABC = 15 / (3/4) = 15 * 4/3 = 20 cm.
Answer: The length of the AB side is 20 cm.
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