Triangles have so many properties. Remember these:
1. Any one side should be less than the sum of the other two.
2. Any one side should be greater than the (positive) difference of the other two.
Special Triangles:
1. 45-45-90: two legs are equal and
hypotenuse = length of leg * square root of 2.
2. 30-60-90: the longer leg = square root of 3 * shorter leg and
hypotenuse = 2 * shorter leg.