A complex number z_1z 1 z, start subscript, 1, end subscript has a magnitude |z_1|=13∣z 1 ∣=13vertical bar, z, start subscript, 1, end subscript, vertical bar, equals, 13 and an angle \theta_1=315^{\circ}θ 1 =315 ∘ theta, start subscript, 1, end subscript, equals, 315, degrees. Express z_1z 1 z, start subscript, 1, end subscript in rectangular form, as z_1=a+biz 1 =a+biz, start subscript, 1, end subscript, equals, a, plus, b, i. Express a+bia+bia, plus, b, i in exact terms. z_1 =z 1 =z, start subscript, 1, end subscript, equals