Question

which equation correctly uses the law of cosines to solve for the missing side length of △pqr? law of cosines: a² = b² + c² - 2bccos(a)

Explanation:

Step1: Identify angle and sides

Angle at P: 39°, adjacent sides: 6 (PR), 8 (PQ); opposite side: p (QR).

Step2: Apply Law of Cosines

Law: \(a^2 = b^2 + c^2 - 2bc\cos(A)\). Here, \(a=p\), \(b=6\), \(c=8\), \(A=39^\circ\). So \(p^2 = 6^2 + 8^2 - 2(6)(8)\cos(39^\circ)\).

Answer:

B. \(p^2 = 6^2 + 8^2 - 2(6)(8)\cos(39^\circ)\)