AREA OF PLANE FIGURES & CIRCLE

ACTIVITY 2

Solve the following problems. 1. Find the area of a square

whose side is 15 dm.  Solution :   A = s² = (15 dm) ² A = 225 dm²

Solve the following problems. 2. Find the area of a triangle

with base 10 cm and height 9 cm.

 Solution :   A = ½bh = ½(10 cm)(9 cm) A = 45 cm²

Solve the following problems. 3. Find the area of a

rectangle whose length and width are 14 dm and 8 dm respectively.

 Solution :   A = lw =(14 dm)(8 dm) A = 112 dm²

Solve the following problems.

4. Find the area of a trapezoid ABCD.

 Solution :   B 8 cm C

A = ½h(b1+b2) 6 cm

= ½(6 cm)(8cm+12 cm) = 3 cm(20 cm) A 12 cm

D A = 60 cm²

5. Find the area of a circle whose radius is 6cm. (Use = 3.14)Solution: A = r² = (3.14)(6 cm)² = (3.14)(36 cm²)A = 36 cm² or 113.04 cm²

Solve the following problems. 6. Find the base of a triangle

if the altitude is 6 cm and the area is 36 cm².

 Solution :   A = ½bh 36 cm² = ½b(6 cm) 36 cm² = 3bcm 12 cm = b

Solve the following problems. 7. Find the area of a

parallelogram with base 14 cm and height 6 cm.

 Solution :   A =bh = 14 cm(6 cm) A = 84 cm²

h = ?

b = 11 cmSolution:Area of a //gram = bh 66 cm² = (11 cm)h 6 cm = h

A

B

D

C

Solve the following problems.

9. Find the area of the figure. 7

5 3 2 3  Solution :   A = (7)(5) – (3)(2) = 35 - 6 A = 29 sq. units

10. Find the area of the shaded figure.

 Solution : step 1. Get the area of the circle.  

A = r² = (3.14)(14cm)² = (3.14)(196 cm²) A = 615.44 cm² step 1. Get the area of

the square. A = s² A = (28 cm)² A = 784 cm²

14 cm

Step 3. Subtract the areaOf the square to the areaOf the circle.

Area of the shaded figure = 784 cm² - 615.44 cm² A = 168. 56 cm²

Solve the following problems. 11. Gen’s garden is 5 meters

wide and 7 meters long. Find the area of the garden.

 Solution :   A =lw = 7m(5 m) A = 35 m²