A triangle is a three sided polygon, What are the different types of triangles?
EQUILATERAL TRIANGLE
A triangle with three congruent (equal) sides and three equal angles.
All the sides length (shown by the line through each of them) and all the angles a the same length:
∠ A = ∠ B = ∠ C = 60º
ISOSCELES TRIANGLE
A triangle with at least two congruent (equal) sides.
Two sides are equal (shown by the lines). Angles opposite the equal sides are equal:
∠ B = ∠ C
RIGHT TRIANGLE
Has only one right angle (90 degrees).
This is shown by the square block at angle B. The side opposite the right angle in called the hypotenuse:
∠ B = 90º
SCALENE TRIANGLE
A triangle that has no congruent (equal) sides.
No sides are equal, no angles are equal
A ≠ B ≠ C
ACUTE-ANGLED
All the angles are less than 90º.
∠ A < 90º, ∠ B < 90º, ∠ C < 90º
OBTUSE-ANGLED
One of the angles is greater than 90º. The longest side is opposite the larget angle.
∠ A >90º