caption: The cosine law Using <PERSON>' theorem in triangle ACD, C
exif: {"Image DocumentName": "The cosine law Using Pythagoras\u2019 theorem in triangle ACD, C", "Image ImageDescription": "b2 = x2 + h2. 1. b. a. h. Also, cos A = x. b. A. B. x. D. c \u2013 x. x = b cos A. 2. In triangle BCD, a2 = (c \u2013 x)2 + h2. We call the perpendicular h for height (not h for hypotenuse). To derive the cosine rule we use both Pythagoras\u2019 Theorem and the cosine ratio. a2 = c2 \u2013 2cx + x2 + h2. a2 = c2 \u2013 2cx + x2 + h2. Substituting and , This is the cosine law. a2 = c2 \u2013 2cb cos A + b2. a2 = b2 + c2 \u2013 2bc cos A.", "Image XResolution": "200", "Image YResolution": "200", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}