In ∆ABC, if a = 8.75 centimeters, c = 4.26 centimeters, and m B = 87°, what is the length of b to two decimal places?

Solution:

cosB= (a^2+c^2-b^2)/2ac

b = sqrt(a^2+c^2-2ac*cosB)

= sqrt(8.75^2+4.26^2-2*8.75*4.26*cos87)

=9.53

So b=9.53cm