Angle Measure in Isosceles Triangle

Triangle PQR is an isosceles triangle where sides PQ and PR are of equal length. If the lengths of sides PQ and PR are both 10 cm, and the base QR measures 12 cm, calculate the measure of the angle QRP.

Use the Law of Cosines, which states that for any triangle with sides of lengths $a$, $b$, and $c$, and the angle $ heta$ opposite side $c$, the relationship is given by:

$$c^2 = a^2 + b^2 - 2ab imes ext{cos}( heta)$$