Using the defects method, which of these relationships represents the law of cosines if the measure of the included angle between the sides a and b of ∆abc is more than 90°?

a. area of square c2 = -area of square a2 – area of square b2 + area of defect1 + area of defect2

b. area of square c2 = area of square a2 + area of square b2 + area of defect1 – area of defect2

c. area of square c2 = area of square a2 + area of square b2 – area of defect1 – area of defect2

d. area of square c