A triangular parcel of ground has sides of length 710 feet, 675 feet, and 535 feet. Find the measure of the largest angle.

Answer 1

The largest angle is the one that is across from the longest side. Since we have no angles given, we must use the Law of Cosines.

a² = b² + c² - 2 (b)(c) Cos A

710² = 675² + 535² - 2(675)(535) Cos A

504100 = 455625 + 286225 - 722250 Cos A. Subtracting the two constants

-237750 = - 722250 Cos A Now dividing

.329179 = Cos A

A = Cos ^-1 .3292

A = 70.78 degrees or 70 degrees 46 minutes 48 seconds