Video: Determining the Type of Angles of the Isosceles Triangle

Determine whether this statement is true or false: the angles of the isosceles triangle are always acute.

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Video Transcript

Determine whether this statement is true or false: the angles of the isosceles triangle are always acute.

The keyword here is “always.” If this is not true, even one time, then the whole statement is false. The statement says the angles of an isosceles triangle are always acute. If we can show one place where the angles in isosceles triangles are not acute, then the statement will be false.

We know that, in an isosceles triangle, two of the sides have to be the same length. Let’s say we have a side length of seven centimetres. Here’s another side of seven centimetres. Connecting the other two vertices makes this a triangle. The created angle is an obtuse angle. It’s larger than 90 degrees and is not an acute angle.

Here’s one example of an isosceles triangle that does not have all acute angles, which makes the given statement false.

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