Triangles are every where you just have to look close. you can use them to make or engineer.
A right triangle has only one corner with exactly 90 degrees.
An acute triangle is where all the corners are less then 90 degrees.
An obtuse triangle is where one corner is more than 90 degrees.
An equilateral triangle has all the sides and angles are the same.
An isosceles triangle has two sides the same and the other is different.
The scalene triangle has all the sides different lengths.