Question

Suppose a triangle has sides a, b, and c, and let theta be the angle opposite the side of length a. If cos theta > 0 what must be true?

A. a2 + b2 > c2
B. a2 + b2 = c2
C. b2 + c2 < a2
D. b2 + c2 > a2

Answer 1

The correct answer is D

Answer 2

When cosθ >0 then , b² + c² > a².

What is triangle?

" Triangle is a 2 dimensional shape which is having three sides and three vertices. Sum of all the interior angles of a triangle is 180°."

Formula used

As per Cosine Rule

For a given ΔABC,

cosθ = $\frac{b^{2} + c^{2} - a^{2} }{2bc}$

According to the question,

cosθ >0

⇒ $\frac{b^{2} + c^{2}-a^{2} }{2bc}$ >0

⇒ b² + c² >a²

Hence, we conclude that Option D is correct.

Learn more about triangles here

https://brainly.com/question/2773823

#SPJ2