Question : The sides of a triangle are in the ratio 5 : 12 : 13 and its perimeter is 90 cm. Find its area (in cm2).
Option 1: 150
Option 2: 270
Option 3: 30
Option 4: 60
Correct Answer: 270
Solution : Let the sides of the triangle be $5x, 12x,$ and $13x$ (where $x$ is a positive constant) The perimeter of the triangle is the sum of its sides: ⇒ $5x+12x+13x=90$ ⇒ $30x = 90$ ⇒ $x = \frac{90}{30}$ = 3 first side = $5x$ = 5 × 3 = 15 cm second side = $12x$ = 12 × 3 = 36 cm third side = $13x$ = 13 × 3 = 39 cm The semi-perimeter is, $s = \frac{15 + 36 + 39}{2}$ = 45 ⇒ Area = $\sqrt{s × (s − a) × (s − b) × (s − c)}$ = $\sqrt{45 × (45 − 15) × (45 − 36) × (45 − 39)}$ = $\sqrt{45 × 30 × 9 × 6}$ = $\sqrt{72900}$ = 270 cm2 Hence, the correct answer is 270.
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Question : What is the area of a triangle having a perimeter of 32 cm, one side of 11 cm, and the difference between the other two sides is 5 cm?
Option 1: $8\sqrt{30}$ cm2
Option 2: $5\sqrt{35}$ cm2
Option 3: $6\sqrt{30}$ cm2
Option 4: $8\sqrt{2}$ cm2
Question : The perimeter of a right triangle is 60 cm and its hypotenuse is 26 cm. What is the area (in cm2) of the triangle?
Option 1: 60
Option 2: 96
Option 3: 90
Option 4: 120
Question : The difference between the semi-perimeter and the sides of ΔPQR are 18 cm, 17 cm, and 25 cm, respectively. Find the area of the triangle.
Option 1: $330\sqrt{510}$ cm2
Option 2: $230\sqrt{510}$ cm2
Option 3: $30\sqrt{510}$ cm2
Option 4: $130\sqrt{510}$ cm2
Question : The sides of a rectangle are in the ratio of 3 : 8 and its area is 1944 cm2. What is its perimeter?
Option 1: 189 cm
Option 2: 208 cm
Option 3: 198 cm
Option 4: 308 cm
Question : The base of a solid right prism is a triangle whose sides are 9 cm, 12 cm, and 15 cm. The height of the prism is 5 cm. Then, the total surface area of the prism is:
Option 1: 180 cm2
Option 2: 234 cm2
Option 3: 288 cm2
Option 4: 270 cm2
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