Video Transcript
How many scalene triangles are
there?
In this question, we’re shown some
different triangles. And we’re asked to count how many
scalene triangles there are. A scalene triangle is a triangle
which doesn’t have any equal sides. In other words, all three sides
have different lengths. Let’s look more closely at the
triangles we’re given. Let’s start with this triangle. We can see that two of its sides
are equal in length. They both measure four
centimeters. And the other side measures
two. This is an isosceles triangle. So, we don’t need to count this
one. We’re just looking for scalene
triangles.
How about this triangle? One of its sides measures four
centimeters, another measures one centimeter, and the third measures three
centimeters. All of the sides of this triangle
are different lengths. So far, we found one scalene
triangle. Let’s look at this triangle
now. Its first side measures four
centimeters, this side measures two centimeters, and this side measures five
centimeters. All of its sides are different
lengths. So, this is also a scalene
triangle. Now, we found two.
Let’s look more closely at this
triangle. We can see that two of its sides
are equal in length. One side or the base is five
centimeters in length, and the other two measure three centimeters. This is an isosceles triangle. And this triangle is also an
isosceles triangle. Two of its sides are equal in
length. One of the sides measures three
centimeters, and two of the sides measure four centimeters.
We looked closely at the lengths of
the sides of each of these triangles. We know that scalene triangles have
sides which are all different lengths. We counted the number of scalene
triangles. There are two.