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 the sides of a triangle are 6 cm, 8 cm, and 10 cm, what is the area of the triangle?

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What is the HCF of 72 and 120?

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A sum of money doubles itself in 5 years at simple interest. What is the rate of interest?

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

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The perimeter of a rectangle is 50 cm, and its length is 15 cm. What is its width?

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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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A number is increased by 20% and then decreased by 20%. What is the net change?

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A man invests Rs. 5000 at 5% per annum simple interest. What is the total amount after 3 years?

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What is the sum of all even numbers between 1 and 100?

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If x + y = 10 and xy = 21, what is the value of x³ + y³?

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