Question

Law of cosines: a2 = b2 + c2 – 2bccos(A) What is the measure of P to the nearest whole degree? 35° 52° 57° 72°

Answer 1

is 57 degrees

Answer 2

Answer: 57°

Given : In triangle PQR, the side PQ is 17, QR is 15, and PR is 14.

We use law of cosine formula

`QR^2 = PR^2 + PQ^2 - 2* PR * PQ * cos (P)`

`15^2 = 14^2 + 17^2 - 2*14 * 17 * cos(P)`

225 = 196 + 289 - 476 cos(P)

225 = 485 - 476 cos (P)

Subtract 485 on both sides

-260 = -476 cos(P)

`(260)/(476)` = cos(P)

P =
`cos^(-1) ((260)/(476))`

P= 56.89202

So measure of angle P is 57 degrees