In this video we're going to look at the four types of triangle. Equilateral triangles, isosceles triangles, right angle triangles, and scalene triangles. And remember what makes them all triangles is that they all have three straight sides.
If we start with the equilateral triangle, the important thing about these is that all three sides are exactly the same length, and all three angles are 60 degrees. So if you need to check whether a triangle is equilateral, just take a look at the angles, or see if the sides have these little dashes on, which would tell you that they're all the same length. Equilateral triangles also have three lines of symmetry, and the rotational symmetry of order 3, which just means that there are three positions within a complete rotation that they look the same. Next up is the isosceles triangle, whose key feature is that they have two sides.
that are the same length. And again, you'll normally see the equal sides drawn with these little dashes on. They also have two angles that are the same size, one line of symmetry, and no rotational symmetry.
Moving on to right angled triangles. The special thing about these is that they have a right angle, which they normally show by putting this little square in the corner. Right angled triangles don't normally have any lines of symmetry, or any rotational symmetry.
But if it happens to be a right angled isosceles triangle, which is where it has a right angle and two sides that are the same length, then it will have one line of symmetry. Last we have the scalene triangle, and the special thing about these is that all three sides are different lengths, and so all three angles are different sizes. This means that they have no lines of symmetry and no rotational symmetry. Anyway, that's everything for this video. So hope you enjoyed it and we'll see you again soon