+157 solve in trigonometric from
[2(cos 100°+sin 100°)] [5(cos300°+i sin 300°)]
+128578 [2(cos 100°+sin 100°)] [5(cos300°+i sin 300°)] =
10 [ -sin (pi / 18) + i cos(pi/18)] [ 1/2 - (√3/2) i] [exact form]
10 [ -0.1736 + .9848i] [ .5 - . 866i] =
10 [ -0.0868 + .4924i + 0.15033i - 0.8528i^2] =
10 [ -0.0868 + 0.8528 + .64273i] =
10 [ .766 + .64273i] =
7.66 + 6.4273i [approximation]
+157 The answer given to this is
10(cos 40°+i sin 40°)
Can you please explain , thank you
