Using the defects method, which relationship represents the law of cosines if the measure of the included angle between the sides a and b of δabc is less 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 c2 = area of square a2 + area of square b2 + area of defect1 + area of defect2