Question

Classify the triangle based on the side lengths 7, 15 and 21 (Points : 2)
right
acute
obtuse
no triangle can be formed with given side lengths

Answer 1

@HunterA i guess acute am i right?

Answer 2

I dont think so....try drawing it out.

Answer 3

@jim_thompson5910 help

Answer 4

I think there's a theorem about this... but I really don't remember much about high school geometry :( But yeah my best guess is to try and draw a scaled-down version so you don't have to draw 21cm line segments...

Answer 5

ask jim or kirb this isn't exactly my area of expertise

Answer 6

ok I found this link: http://www.algebra.com/algebra/homework/Triangles/Triangles.faq.question.403585.html

Answer 7

@jim_thompson5910 need your help

Answer 8

Based on the link... compute 21^2. Now, compute sum 7^2+15^2
If 21^2 is larger than that sum, it's obtuse, if it's less it's acute. If it's equal, it's a right angle triangle

Answer 9

a^2 + b^2 ? c^2

7^2 + 15^2 ? 21^2

49 + 225 ? 441

274 ? 441

274 < 441


since a^2 + b^2 < c^2, this means that we're dealing with an obtuse triangle (since the square of the longest side is larger)

Answer 10

I don't really remember learning that in high school lol. But it actually makes sense

Answer 11

jim was correct yay

Answer 12

rule:

if a^2 + b^2 = c^2, then ABC is a right triangle

if a^2 + b^2 > c^2, then ABC is an acute triangle

if a^2 + b^2 < c^2, then ABC is an obtuse triangle

where c is the longest side