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# Area of triangle PQR is 100 cm² (Fig. 9.20). If altitude QT is 10 cm, then its base PR is

a. 20 cm

b. 15 cm

c. 10 cm

d. 5 cm

**Solution:**

It is given that

__Area of triangle__ PQR = 100 cm²

We know that

Area of triangle = 1/2 × base × height

Area of triangle PQR = 1/2 × PR × QT

Substituting the values

100 = 1/2 × PR × 10

By further calculation

PR = (100 × 2)/ 10

So we get

PR = 20 cm

Therefore, PR is 20 cm.

**✦ Try This: **81 unit squares are joined to form a rectangle with the least perimeter. Perimeter of the rectangle is

**☛ Also Check: **NCERT Solutions for Class 7 Maths Chapter 11

**NCERT Exemplar Class 7 Maths Chapter 9 Problem 15**

## Area of triangle PQR is 100 cm² (Fig. 9.20). If altitude QT is 10 cm, then its base PR is a. 20 cm, b. 15 cm, c. 10 cm, d. 5 cm

**Summary:**

Area of triangle PQR is 100 cm² (Fig. 9.20). If altitude QT is 10 cm, then its base PR is 20 cm

**☛ Related Questions:**

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- In Fig. 9.21, if PR = 12 cm, QR = 6 cm and PL = 8 cm, then QM is a. 6 cm, b. 9 cm, c. 4 cm, d. 2 cm

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