# Video: Determining the Type of a Given Triangle

Which of the following describes the given shape? [A] isosceles triangle [B] right triangle [C] scalene triangle [D] obtuse triangle [E] equilateral triangle.

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### Video Transcript

Which of the following describes the given shape? A) Isosceles triangle, B) right triangle, C) scalene triangle, D) obtuse triangle, and E) equilateral triangle.

So that we can actually decide which one of these triangles actually describes our shape, we’ll look at a definition for each. If we start with an isosceles triangle, well, an isosceles triangle is a triangle with two equal sides. A right triangle is a triangle, where one angle is 90 degrees. A scalene triangle is a triangle that has no sides of the same length. An obtuse triangle is one that has one obtuse and that’s an angle greater than 90 degrees and two acute angles. And then, finally, an equilateral triangle is one that has three equal sides.

Okay, great, so we have definitions for each of our triangles. And these aren’t exhaustive actually because for each of our types of triangles, there are other relationships to do with angles et cetera, which will also be apparent. But however, it’s gonna help us with solving this problem.

So if we look back at our triangle, we see these two lines and what they tell us is that these two sides are actually equal. So therefore, we know that actually our triangle has two equal sides. So therefore, answer A isosceles triangle best describes our given shape.