How do you know when a triangle is obtuse when you are given only the sides?

Question

I'm given a triangle and the measures of all three sides. They ask me whether its acute obtuse or right. How am I supposed to know?

Answer 1

hmmm it's in ur notes. if the 2 legs are less than the hypotenuse its obtuse and if they are greater than the hypotenuse its acute and if they are are equal its right

Answer 2

find a way to draw the triangle on a sheet of paper.or cut lengths of paper that represent the side lengths. You don't need to draw the sides of the triangle or cut the side lengths to scale.... like if they say that one side is 120 inches... you are obviously not going to cut a piece of paper to get a 120 inches long side. Just makes sure that when you draw or cut... that the 3 side lengths are using the same scale relative to each other. e.g. if you were given 30 in., 40 in., and 50 in.... I would use a scale of 1 in to represent 10 inches... and cut out 3 strips, one 3 in. one 4 in. and one 5 in. When I put the sides together... I will learn that what I have is a right triangle. The scale helps... because what you have will be a smaller similar triangle to what is given. A obtuse triangle half the size, or triple the size will always have the same angle measurements, and will always remain obtuse. Same is true for an acute triangle. So try to simplify the given measurements into something workable. A smaller triangle with the same ratio of sides to each other... and doing that will reveal to you whether you have an acute triangle or and obtuse... hope this explanation helps!!!

Answer 3

Ummm.....triangles aren't obtuse, Angles may be.

Look: angles between 0 and 90 degrees are known as 'acute' angles. They are the 'sharp' ones.
A 'right angle' is one of exactly 90 degrees.
Angles between 90 and 180 degrees are known as obtuse.
The last type of angle is known as 'reflex', these are between 180 and 360 degrees.

There are also three types of triangles.
Equilateral: all three sides have the same length and all angles are 60 degrees.
Isocseles: Two sides are equal length, and the angles that touch the unequal line are the same.
Right Angle Triangle: This one has a right angle (90 degrees) at one end.

I think you need to find the angles of all the sides of the triangle.
Here's how to do a triangle with only the sides.
Eg: 3cm, 4cm and 5cm triangle
STEP 1= Draw the line of 3 cm on a piece of paper.

______
3cm

STEP 2= Grab a compass, and place it on 4 cm from the tip to the end. Then, place the sharp line in the end of the 3cm line, and do a faint circle in your paper.
STEP 3= Do the same at the other side of the 3cm line with the compass placed at 5cm.
STEP 4= You get a cross between the circles, that is your third point of the triangle. Connect the third point to the ends of the 3cm line.

You got a triangle!!

OK, now to get the angles:
Use a pretractor to find all 3 angles, and (from the info up top) find if the angles are either acute, obtuse or right angles. (There are no reflex angles on a triangle).

Answer 4

Let a and b be the shorter sides and c be the longest side.

If a^2+b^2=c^2, it's a right triangle.
If a^2+b^2 If a^2+b^2>c^2, it's an acute triangle

Do you see why?

Answer 5

if one of the angles is over a 90 degree angle and the other 2 angles are smaller than a 90 degree angle.

Answer 6

use a stupid protractor!!!!