Triangle Angle Sum
Triangles · Class VII
Choose two angles A and B; the third C makes the angles add to 180.
- Third angle C50
- Angle sum check180
- Valid triangle? (1 yes)1
Formulas in this lab
- Third angle C
- Angle sum check
- Valid triangle? (1 yes)
Frequently asked questions
▶Why do the angles of a triangle add up to 180 degrees?
This is a basic geometry rule: the three interior angles of any triangle always sum to 180. So if two angles are 60 and 70, the third must be 50. The lab uses this to compute the third angle from the other two.
▶How do I use the triangle angle sum lab?
Slide angle A and angle B between 1 and 178 degrees. The lab finds the third angle C = 180 - A - B and confirms the sum A + B + C is always 180. Try A = 90 and B = 45 to see C = 45, a right-angled isoceles triangle.
▶How can I check if three angles really form a triangle?
Add them: if they total exactly 180 and each is between 0 and 180, they form a valid triangle. The lab refuses to give a positive C if A + B is already 180 or more, telling you the triangle is impossible.
▶Acute vs obtuse vs right triangle: how to tell?
If all three angles are below 90, the triangle is acute (e.g. 60-60-60). If exactly one is 90, it is right-angled. If one is above 90, it is obtuse. The lab makes this easy: set A and B and read off C to classify the triangle in one second.