Topics

Find the area of a triangle whose sides are 7 cm., 8 cm. and 9 cm.

 A) 28.642 sq. cm. B) 26.832 sq. cm. C) 24.564 sq. cm. D) 22.832 sq. cm.

 B) 26.832 sq. cm.

Area of the triangle = $$\Large \sqrt{s \left(s-a\right) \left(s-b\right) \left(s-c\right) }$$

$$\Large s = \frac{a+b+c}{2}$$

$$\Large s = \frac{7+8+9}{2}=\frac{24}{2}$$= 12 cm.

Area of the triagle =$$\Large \sqrt{12 \left(12-7\right) \left(12-8\right) \left(12-9\right) }$$

=$$\Large \sqrt{12 \times 5 \times 4 \times 3} = \sqrt{36 \times 4 \times 5} = 6 \times 2\sqrt{5}$$

=$$\Large 6 \times 2.236=12 \times 2.236=26.832 sq. cm.$$

Part of solved Area and perimeter questions and answers : >> Elementary Mathematics >> Area and perimeter

Similar Questions
1). If the ratio between the radius of the circles is 4 : 3 then what is ratio of the area between the two circles:
 A). 13 : 17 B). 4 : 5 C). 16 : 9 D). 3 : 5
2). The perimeter of a semi circle is 36 cm. What is its diameter?
 A). 35 cm. B). 28 cm. C). 21 cm. D). 14 cm.
3). The ratio between the length and breadth of a stadium is 5 : 3 and its perimeter is 256 metres. What will be the cost of leveling the ground of the stadium at the rate of Rs.2.50 per sq. metre.
 A). Rs.9600 B). Rs.8400 C). Rs.7200 D). Rs.6400
4). Find the area of square field whose diagonal is 24 mtrs.
 A). 288 sq.m. B). 488 sq.m. C). 216 sq.m. D). 284 sq.m.
5). The length and breadth of a rectangular field are in the I ratio 4 : 3. If the cost of cultivating the field at Rs. 5 per sq. metre is Rs.6000. Find the dimensions of the field.
 A). 12 m, 10 m. B). 24 m. 10 m. C). 40 m. 30 m. D). 16 m. 10 m.

6). A rectangular field is 125 m. long and 65 m. broad. A path of uniform width of 2.5 metres runs around the field inside it. Find the area of the path?
 A). 925 sq. mts. B). 875 sq. mts. C). 675 sq. mts. D). None of these .