If two vectors are represented both in magnitude and direction by the two adjacent sides of a triangle taken in an order, then their resultant is given by the third side taken in the reverse order.
Resultant vector :
R = sqrt of A^2 + B^2 + 2ABcosθ
given :
A = 200 units
B = 300 units
θ = 30 degrees
∴ R = sqrt of 200^2 + 300^2 + 2(200)(300)cos35
the answer is 477.805656