If base and the altitude of a triangle are 3 m -2 n and 3 m -4 n repectively- then the area of the triangle isA- 1-2-9 m 2-6 mn -8 n 2B- 1-2-9 m 2-6 mn -8 n 2C- 1-2-9 m 2-6 mn -8 n 2D- 5-2-9 m 2-6 mn -8 n 2

The correct option is C 1/2× (9m^2 6mn 8n^2) Required area = 1/2× base × height =1/2× (3m+2n) × (3m 4n) =1/2×(3m(3m 4n)+2n(3m 4n)) =1/2× (9m^2 12mn+6nm 8n^2) = ...

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Byju's Answer

Standard VII

Mathematics

Use of Algebraic Expressions in Formula of Area of Figures

If base and t...

Question

If base and the altitude of a triangle are $(3 m + 2 n)$ and $(3 m - 4 n)$ repectively, then the area of the triangle is _____.

$\frac{1}{2} \times (9 m^{2} + 6 m n - 8 n^{2})$

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$\frac{1}{2} \times (9 m^{2} - 6 m n + 8 n^{2})$

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$\frac{1}{2} \times (9 m^{2} - 6 m n - 8 n^{2})$

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$\frac{1}{2} \times (9 m^{2} + 6 m n + 8 n^{2})$

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Solution

The correct option is C
$\frac{1}{2} \times (9 m^{2} - 6 m n - 8 n^{2})$

$Required area = \frac{1}{2} \times b a s e \times h e i g h t$

$= \frac{1}{2} \times (3 m + 2 n) \times (3 m - 4 n)$

$= \frac{1}{2} \times (3 m (3 m - 4 n) + 2 n (3 m - 4 n))$

$= \frac{1}{2} \times (9 m^{2} - 12 m n + 6 n m - 8 n^{2})$

= $\frac{1}{2} \times (9 m^{2} - 6 m n - 8 n^{2})$

Suggest Corrections

If base and the altitude of a triangle are (3m+2n) and (3m−4n) repectively, then the area of the triangle is _____.

The correct option is C 12×(9m2−6mn−8n2) Required area = 12×base×height =12×(3m+2n)×(3m−4n) =12×(3m(3m−4n)+2n(3m−4n)) =12×(9m2−12mn+6nm−8n2) = 12×(9m2−6mn−8n2)

If base and the altitude of a triangle are $(3 m + 2 n)$ and $(3 m - 4 n)$ repectively, then the area of the triangle is _____.