550^2 = 45^2 + x^2 - 2*45x*cos100°
show step by step on how to find x
draw triangle
law of cosines
c^2 = a^2 + b^2 - 2 a b cos C
a = 45
b = x
c = 550 I suspect should be 55
law of sines
sin 100/550 or 55 = sin A/45
find angle A
then angle B = 180 - 100 - A
then
sin B/x = sin 100 / 550 or 55
sin A/