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Read the given statements carefully and ...

Read the given statements carefully and select the correct option.
Statement-I : A field is in the shape of quadrilateral ABCD, `angleC = 90^@`, AB = 9 m, BC = 12 m, CD = 5 m and AD = 8 m, then the area of the field is 70 `m^2`.
Statement-II: The semi-perimeter of a triangle having sides 13 cm, 14 cm and 15 cm is 21 cm.

A

Both Statement-I and Statement-II are true.

B

Both Statement-I and Statement-II are false.

C

Statement-I is true but Statement-II is false.

D

Statement-I is false but Statement-II is true.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the two statements provided and determine their validity step by step. **Step 1: Analyze Statement I** - We have a quadrilateral ABCD with the following properties: - \( \angle C = 90^\circ \) - \( AB = 9 \, \text{m} \) - \( BC = 12 \, \text{m} \) - \( CD = 5 \, \text{m} \) - \( AD = 8 \, \text{m} \) **Step 2: Calculate the area of triangle BCD** - Since \( \angle C = 90^\circ \), we can use the formula for the area of a right triangle: \[ \text{Area}_{BCD} = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times BC \times CD = \frac{1}{2} \times 12 \times 5 \] \[ = \frac{1}{2} \times 60 = 30 \, \text{m}^2 \] **Step 3: Calculate the length of diagonal BD using Pythagorean theorem** - In triangle BCD, we can find \( BD \): \[ BD^2 = BC^2 + CD^2 = 12^2 + 5^2 = 144 + 25 = 169 \] \[ BD = \sqrt{169} = 13 \, \text{m} \] **Step 4: Calculate the area of triangle ABD using Heron's formula** - First, we find the semi-perimeter \( s \): \[ s = \frac{AB + AD + BD}{2} = \frac{9 + 8 + 13}{2} = \frac{30}{2} = 15 \, \text{m} \] - Now, we apply Heron's formula: \[ \text{Area}_{ABD} = \sqrt{s(s - AB)(s - AD)(s - BD)} = \sqrt{15(15 - 9)(15 - 8)(15 - 13)} \] \[ = \sqrt{15 \times 6 \times 7 \times 2} \] \[ = \sqrt{15 \times 84} = \sqrt{1260} \] - Approximating \( \sqrt{1260} \) gives us about \( 35.5 \, \text{m}^2 \). **Step 5: Calculate the total area of quadrilateral ABCD** - The total area of quadrilateral ABCD is: \[ \text{Area}_{ABCD} = \text{Area}_{ABD} + \text{Area}_{BCD} = 35.5 + 30 = 65.5 \, \text{m}^2 \] **Step 6: Validate Statement I** - Statement I claims the area is \( 70 \, \text{m}^2 \), which is incorrect since we calculated it to be \( 65.5 \, \text{m}^2 \). **Step 7: Analyze Statement II** - The sides of the triangle are \( 13 \, \text{cm}, 14 \, \text{cm}, 15 \, \text{cm} \). - Calculate the semi-perimeter: \[ s = \frac{13 + 14 + 15}{2} = \frac{42}{2} = 21 \, \text{cm} \] - Statement II is true. **Final Conclusion** - Statement I is false, and Statement II is true. **Correct Option: Statement 1 is false, Statement 2 is true.** ---
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