Answer:
14.55'
Step-by-step explanation:
Cosine rule
c^2 = a^2 + b^2 - 2ab cos(C)
here
a=11
b=23
C = 150°
Substitute in cosine rule,
c^2 = 11^2 + 23^2 - 2(11)(23) cos (150°)
= 121 + 529 -2 (11) (23) sqrt(3)/2
=211.791
c = sqrt(211.791)
= 14.55