We can proceed in solving the problem since all information are given such as 2*4*5costheta. we have a=4, b=5, and C=theta let us solve for "c" using Pythagorean c²=a²+b² c²=4²+5² c=6.4 Solving for theta or C c²=a²+b²-2abcosC 6.4²=4²+5²-2*4*5*cosC C=90
