Question

Suppose a triangle has sides a, b, and c, and that a2 + b2 < c2. Let be the measure of the angle opposite the side of length c. Which of the following must be true? Check all that apply.A. The triangle is not a right triangle.B. cos > 0C. cos < 0D. a2 + b2 - c2 = 2abcos

Answer 1

can you type your question in full? There is information missing

Answer 2

Since a^2 + b^2 is NOT EQUAL to c^2, it is NOT a Right triangle..

The other Options seems to be unclear...

Answer 3

Trigonometric ratios can be only applied in a right triangle.. Since it is not a right triangle, options B and C are not correct...

D I'm not sure

Answer 4

fI the sum of the squares of two of the sides of the triangle is less than the square of the length of the third side, then the triangle is obtuse. Theta is an obtuse angle.

http://math.wikia.com/wiki/Triangle_inequality

Therefore, the triangle is not a right triangle and option A is true.

Answer 5

B. cos (theta) > 0. Theta is obtuse. The cosine of an obtuse angle is negative.
Option B is incorrect.

C. cos(theta) < 0. Theta is obtuse. The cosine of an obtuse angle is negative.
Option C is correct.

D. a^2 + b^2 -c^2=2ab * cos(theta)
This is the Law of Cosines. Does it hold true for this obtuse triangle?

@Karla120896