Area and Perimeter of Triangles Worksheets

**Page 1**

1.

What is the height of ΔPQR, if its area is 8 in.^{2} and the measure of QR is 4 in.?

a. | 32 in. | ||

b. | 4 in. | ||

c. | 2 in. | ||

d. | None of the above |

[Formula.]

8 =

[Substitute the value of area of ΔPQR.]

QR × PS = 16

[Multiply each side by 2.]

4 × PS = 16

[Substitute QR = 4.]

PS = 4

[Divide each side by 4.]

So, height of the ΔPQR = 4 in.

Correct answer : (2)

2.

Find the perimeter of the equilateral triangle LMN.

a. | 18 m | ||

b. | 28 m | ||

c. | 36 m | ||

d. | 16 m |

[Sum of all three sides.]

LM = MN = LN = 6 m

[Since LMN is an equilateral triangle.]

Perimeter = 6 + 6 + 6 = 18

[Substitute the values and add.]

So, the perimeter of ΔLMN is 18 m.

Correct answer : (1)

3.

Find the perimeter of the triangle PQR.

a. | 48 cm | ||

b. | 120 cm | ||

c. | 55 cm | ||

d. | 40 cm |

From the figure, the lengths of the sides are 8 cm, 15 cm and 17 cm.

The perimeter of the triangle PQR = 8 + 15 + 17 = 40 cm

Correct answer : (4)

4.

Find the area of an equilateral triangle, if its perimeter and height are 30 cm and 5$\sqrt{3}$ cm respectively.

a. | 18 cm ^{2} | ||

b. | 36 cm ^{2} | ||

c. | 50$\sqrt{3}$ cm ^{2} | ||

d. | 25$\sqrt{3}$ cm ^{2} |

Base of the triangle = 30 ÷ 3 = 10 cm

The area of a triangle =

=

So, the area of the triangle is 25

Correct answer : (4)

5.

What is the area of the triangle?

a. | 64 cm ^{2} | ||

b. | 88 cm ^{2} | ||

c. | 84 cm ^{2} | ||

d. | 45 cm ^{2} |

Area of a triangle =

=

= 84

Area of the triangle is 84 cm

Correct answer : (3)

6.

What is the area of the triangle?

a. | 40 in. ^{2} | ||

b. | 80 in. ^{2} | ||

c. | 24 in. ^{2} | ||

d. | 36 in. ^{2} |

Area of a triangle =

=

= 80

So, area of the triangle is 80 in.

Correct answer : (2)

7.

Find the area of a triangle whose base is 9 in. and height is 10 in.

a. | 47 in. ^{2} | ||

b. | 45 in. ^{2} | ||

c. | 49 in. ^{2} | ||

d. | 44 in. ^{2} |

=

[Substitute base = 9 and height = 10.]

=

[Simplify.]

The area of the triangle is 45 in.

Correct answer : (2)

8.

The area of a triangle is 12 in.^{2} and base of the triangle is 3 in. Find the height of the triangle.

a. | 9 in. | ||

b. | 7 in. | ||

c. | 8 in. | ||

d. | 10 in. |

12 =

[Substitue the values of Area and Base.]

12 x 2 = 3 x height

[Multiply each side by 2.]

[Divide each side by 3.]

8 = height

The height of the triangle is 8 in.

Correct answer : (3)

9.

Find the length ($b$) of the base of the triangle ABC in the figure, if area of the triangle ABC is 10 cm^{2}.

a. | 2 cm | ||

b. | 4 cm | ||

c. | 5 cm | ||

d. | 6 cm |

[Substitute the value of the area of the triangle.]

BC x AD = 20

[Multiply both sides by 2.]

BC x 4 = 20

[Substitute AD = 4 cm.]

BC =

[Divide each side by 4.]

The length of the base of the triangle ABC is 5 cm.

Correct answer : (3)

10.

Find the perimeter of the triangle ABC.

a. | 12 cm | ||

b. | 10 cm | ||

c. | 14 cm | ||

d. | 20 cm |

From the figure, the lengths of the sides are 4 cm, 5 cm and 3 cm.

The perimeter of the triangle ABC = 4 + 5 + 3 = 12 cm

[Add.]

Correct answer : (1)

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