Lengths of sides of a triangle are 3 cm, 4 cm and 5 cm. The triangle is
a. Obtuse angled triangle
b. Acute-angled triangle
c. Right-angled triangle
d. An Isosceles right triangle

Solution:

Given, the lengths of sides of a triangle are 3 cm, 4 cm and 5 cm.

We have to determine the type of triangle.

Consider a triangle ABC,

Let AB = 4 cm, BC = 3 cm and AC = 5 cm

By using pythagorean theorem,

AC² = AB² + BC²

LHS : AC²

AC² = (5)²

= 25

RHS : AB² + BC²

AB² = (4)² = 16

BC² = (3)² = 9

AB² + BC² = 16 + 9

= 25

LHS = RHS

Therefore, the triangle is a right angled triangle.

✦ Try This: The sides of a triangle are 5 cm, 7 cm and 9 cm. Is the triangle right angled. Justify your answer

☛ Also Check: NCERT Solutions for Class 7 Maths Chapter 6

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NCERT Exemplar Class 7 Maths Chapter 6 Problem 7

Lengths of sides of a triangle are 3 cm, 4 cm and 5 cm. The triangle is: a. Obtuse angled triangle, b. Acute-angled triangle, c. Right-angled triangle, d. An Isosceles right triangle

Summary:

Lengths of sides of a triangle are 3 cm, 4 cm and 5 cm. The triangle is a right angled triangle

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