Topic Details (Notes format)

How to Classify Triangles by Sides and Angles

Subject: Mathematics

Book: Maths Mastery

Triangles can be classified by sides—equilateral (all sides equal), isosceles (two equal sides), scalene (all sides different)—or by angles—acute (all angles < 90°), right (one angle = 90°), obtuse (one angle > 90°). For example, a triangle with side lengths 3, 3, 5 is isosceles, while one with angles 30°, 60°, 90° is right-angled. Such classifications underlie geometry proofs and real-world designs like roof trusses, bridging shape fundamentals with practical engineering. Identifying the triangle type sets the stage for using the right formulas or theorems to solve deeper geometric questions.

Practice Questions

If a+b = 10 and ab = 21, what is the value of (a-b)^2?

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If a number is divisible by 9, it is also divisible by which of the following?

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What is the LCM of 15 and 20?

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What is the sum of the first 20 odd numbers?

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If a = 5 and b = 12, what is the length of the hypotenuse of a right triangle?

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If a = 4 and b = 5, what is the value of (a+b)^2?

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The sides of a triangle are 13 cm, 14 cm, and 15 cm. What is its area?

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