It means Father, Son, and Holy Spirit. Kind of like the cross.
It means 3 angles that can be found in a triangle.
Unless it is a religious triangle it does not have to have any angels! Seriously, though, a triangle does not have to have a 90 degree angle. In terms of its angles, the only requirement is that the measures of the three angles adds to 180 degrees (or pi radians).
No, the words "nativity" and "scene" are not in themselves religious terms. Look them up on the dictionary and see what they mean.
To conclude, or deduce, as in, "from the fact that the triangle is equilateral, and the fact that a triangle is isoceles if and only if the base angles are equal, we can infer that it is also equiangular."
a right triangle
The answer depends on what you mean by "mean of triangle". There is no such geometric term.
It means to be responsible and guide things in a good and proper direction and to not be wasteful.
If you mean "triangle", a triangle can never have two parallel sides.If you mean "triangle", a triangle can never have two parallel sides.If you mean "triangle", a triangle can never have two parallel sides.If you mean "triangle", a triangle can never have two parallel sides.
Dated, or old terms.
Triangle-ception.
There is no anagram for relating in mathematical terms.
In mathematical terms, "five times triangle" is not a standard expression. However, if we interpret "triangle" as a variable or a value, then "five times triangle" would simply mean multiplying that value by five. For example, if triangle equals 3, then five times triangle would equal 15. If you meant something else, please provide additional context!