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Chapter 18

Pythagoras Theorem — Statement I-II Type Questions

Class - 7 Concise Mathematics Selina



Statement I-II Type Questions

Question 10

Statement 1: The sides of a triangle are of length 6 cm, 4.5 cm and 7.5 cm. The angle opposite to the side 7.5 cm is 90°.

Statement 2: A triangle having one right angle is called a right-angled triangle.

Which of the following options is correct?

  1. Both the statements are true.

  2. Both the statements are false.

  3. Statement 1 is true, and statement 2 is false.

  4. Statement 1 is false, and statement 2 is true.

Answer

Here the longest side is 7.5 cm.

(7.5)2 = 7.5 × 7.5 = 56.25

(4.5)2 + 62 = 20.25 + 36 = 56.25

Since (7.5)2 = (4.5)2 + 62, Pythagoras theorem holds, so the angle opposite the longest side 7.5 cm is 90°. Thus, statement 1 is true.

A triangle having one right angle is called a right-angled triangle. Thus, statement 2 is true.

Hence, option 1 is the correct option.

Question 11

Statement 1: A right angled triangle may be an isosceles triangle.

Statement 2: Vertex angle of a right angled isosceles triangle is 90°.

Which of the following options is correct?

  1. Both the statements are true.

  2. Both the statements are false.

  3. Statement 1 is true, and statement 2 is false.

  4. Statement 1 is false, and statement 2 is true.

Answer

A right-angled triangle may be an isosceles triangle, because a triangle can have a right angle and, at the same time, two equal sides (an isosceles right-angled triangle).

Thus, statement 1 is true.

In a right-angled isosceles triangle, the two equal sides contain the right angle, so the vertex angle (the angle between the two equal sides) is 90°.

Thus, statement 2 is true.

Hence, option 1 is the correct option.

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