Ah hah! That little word "which" is pretty much a giveaway ... I'll just bet there was
some kind of a list of choices that was supposed to go along with the question, but
somehow got lost.
Anyway, the correct inequality is: 3 < x < 13 .
5 < x < 9
4 < x < 20
No
A triangle with all angles measuring less than 90 degrees?That's an 'acute' triangle.
A triangle with one angle measuring 90˚ is a right triangleIt's a right triangle because the 90˚ angle is a right angle
5 < x < 9
4 < x < 20
This is not an equilateral triangle.
No
No but an isosceles triangle is quite possible having 2 equal sides
Sure, that is exactly what the triangle inequality tells us!
The triangle inequality theorem states that any side of a triangle is always shorter than the sum of the other two sides.
It is not possible to have a triangle with sides of those lengths. The two shortest sides of a triangle must always add to more than the longest side. This is known as the triangle inequality.
no
no.
Yes simply with a protractor and a measuring device.
Doesn't it depend on what type of triangle it is? And which sides you are measuring? And which side it's laying on?