If the average (arithmetic mean) of the measures of two noncongruent angles of an isosceles triangle is \( 70^{\circ} \), which of the following is the measure of one of the angles of the triangle?
(A) \( 50^{\circ} \)
(B) \( 60^{\circ} \)
(C) \( 80^{\circ} \)
(D) \( 90^{\circ} \)
(E) \( 100^{\circ} \)