Answer :
Answer:
1. A triangle can have **at most one** right angle.
2. True. A triangle in which any one angle is a right angle is called a Right-angled triangle.
3. An obtuse angle is more than **90 degrees** but less than **180 degrees**.
4. False. The sides of an equilateral triangle are **all the same length**.
5. The sum of three angles of a triangle is equal to **180 degrees**.
6. True. Each angle of an acute-angled triangle is less than **90 degrees**.
7. In an isosceles triangle, any **two** sides are equal.
8. False. A triangle is a **three-sided** polygon.
9. The sides of an **equilateral** triangle are of equal length.
10. False. The sum of three angles of a triangle is **exactly 180 degrees**.
11. A triangle in which all sides are different lengths is called a **scalene** triangle.
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