A parallelogram has side lengths of 13 and 17 and an angle that measures 64°. Law of cosines: a2 = b2 + c2 – 2bccos(A) What is x, the length of the diagonal, to the nearest whole number? 16 18 19 21
Given that the parallelogram has the dimensions given above, the value of x can be calculated using cosine rule as follows; a^2=b^2+c^2-2bcCosA thus; x^2=13^2+17^2-2*13*17*cos 64 x^2=169+289-442cos64 x^2=458-193.76 x^2=264.24 thus; x=sqrt264.24 x=16.2555 The answer is 16
