Area Class 8 Long Question Answer

Area Class 8 Long Question Answer

Area Class 8 Long Question Answer

Question 1.

The area of a trapezium is 34 cm² and the length of one of the parallel sides is 10 cm and its height is 4 cm. Find the length of the other parallel side.

Solution:

Let the length of the required side be x cm.

Then, area of the trapezium

= [[latex]\frac{1}{2}[/latex] × (10 + x) × 4] cm²

= 2(10 + x) cm².

But, the area of the trapezium

= 34 cm²

∴ 2(10 + x) = 34.

or 10 + x = 17

or x = 17 — 10 = 7.

Hence, the other side = 7 cm.

Question 2.

Find the area of a rhombus whose side is 5 cm and whose altitude is 4.8 cm. If one of its diagonals is 8 cm long, find the length of the other diagonal.

Solution:

Let ABCD be a rhombus of side 5 cm and whose altitude DE = 4.8 cm. Also, one of its diagonals, BD = 8 cm.

Area of the rhombus ABCD

= b × h

= (5 × 4.8) cm² = 24 cm².

Also, area of the rhombus ABCD

= [latex]\frac{1}{2}[/latex] × AC × BD

So, [latex]\frac{1}{2}[/latex] × AC × 8 = 24.

or AC = 6 cm.

Hence, the other diagonal is 6 cm.