Question

Use the stated variant of the Law of Cosines, a2=b2+c2−2bc⋅cosA
, to find the value of angle A
in a right triangle, where a=8
, b=15
, and c=17
. Round your answer to the nearest whole number.(1 point)
A=
degrees

Answer 1

Using a^2 = b^2 + c^2 − 2bc cos A,

cos A = (b^2 + c^2 − a^2) / (2bc) = (225 + 289 − 64) / (2·15·17) = 450/510 = 15/17 ≈ 0.88235.

A = arccos(15/17) ≈ 28° (to the nearest whole degree).