Area of an Isosceles Triangle

Q.

If an isosceles triangle has a perimeter of $18cm$ and base $8cm$, then its area is ___ .

1. $45c{m}^2$

2. $68c{m}^2$

3. $12c{m}^2$

4. $20c{m}^2$

Q. The sides of a triangle are 39 cm, 25 cm and 56 cm. Find it's area.

Q. The sides of a triangle are 21 cm, 17 cm and 10 cm. Find it's area.

Q. The perimeter of an isosceles triangle is 32 cm. The ratio of the equal side to its base is 3:2.
Find the area of the triangle.

1. $\sqrt{32}c{m}^2$
2. $32c{m}^2$
3. $32\sqrt{4}c{m}^2$
4. $32\sqrt{2}c{m}^2$

Q.

Assertion : Area of a triangle $=\sqrt{\left.s(s-a\right)(s-b)(s-c)}$ where $a,bandc$ are the sides of the triangle and $s=\frac{a+b+c}{2}$

Reason: Area of a triangle $=\frac{1}{2}\times base\times height$.

Which of the following is correct?

1. A is true and $R$ is false

2. $\mathrm{A}$ is false and $R$ is true.

3. Both $\mathrm{A}$ and $\mathrm{R}$ are true and $\mathrm{R}$ is the correct explanation of $A$.

4. Both $A$ and $R$ are true but $R$ is not the correct explanation of $A.$

Q. In $△ABC,AB=7,AC=8,BC=9$.Find the perimeter of triangle.

Q.

In the given shelf which is right angled at A, AB = AC = 48 inches. Find the area of the shelf.

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1. 1155 sq. inches

2. 1152 sq. inches

3. 1142 sq. inches

4. 1158 sq. inches

Q.

If an isosceles triangle has a perimeter of $18cm$ and base $8cm$, then its area is ___ .

1. $45c{m}^2$

2. $68c{m}^2$

3. $12c{m}^2$

4. $20c{m}^2$

Q. Calculate the area of the pentagon ABCDE, where AB = AE and with dimensions as shown in Fig. 36.