Question

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

Answer 1

this is an animation that shows defect

Answer 2

http://illuminations.nctm.org/Activity.aspx?id=4198