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STATEMENT-1 : If the angle of a convex ...

STATEMENT-1 : If the angle of a convex polygon are in A.P. ` 120^(@) , 125^(@) , 130^(@)` …, then it has 16 sides and
STATEMENT-2 : The sum of the angles of a polygon of x sides is `(n -2) 180^(@)`

A

Statement-1 is True , Statement-2 is True, Statement -2 is a correct explanation for Statement-1

B

Statement-1 is True , Statement-2 is True, Statement -2 is NOT a correct explanation for Statement-1

C

Statement-1 is True, Stetement-2 is False.

D

Statement-1 is False, Statement-2 is True

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we will analyze both statements and prove their validity step by step. ### Step 1: Understanding the Angles of the Polygon The angles of the convex polygon are given in an arithmetic progression (A.P.) as follows: - First angle (A) = 120° - Second angle = 125° - Third angle = 130° - Common difference (d) = 5° ### Step 2: Finding the Number of Sides (N) The formula for the sum of the interior angles of a polygon with N sides is: \[ \text{Sum of angles} = (N - 2) \times 180° \] ### Step 3: Sum of Angles in A.P. The sum of the angles in A.P. can be calculated using the formula for the sum of an A.P.: \[ S_N = \frac{N}{2} \times (2A + (N - 1)D) \] Substituting the values: - A = 120° - D = 5° Thus, we have: \[ S_N = \frac{N}{2} \times (2 \times 120 + (N - 1) \times 5) \] \[ S_N = \frac{N}{2} \times (240 + 5N - 5) \] \[ S_N = \frac{N}{2} \times (5N + 235) \] \[ S_N = \frac{5N^2 + 235N}{2} \] ### Step 4: Setting the Two Expressions for the Sum Equal Now, we equate the two expressions for the sum of the angles: \[ \frac{5N^2 + 235N}{2} = (N - 2) \times 180 \] ### Step 5: Simplifying the Equation Multiply both sides by 2 to eliminate the fraction: \[ 5N^2 + 235N = 2(N - 2) \times 180 \] \[ 5N^2 + 235N = 360N - 720 \] ### Step 6: Rearranging the Equation Rearranging gives us: \[ 5N^2 + 235N - 360N + 720 = 0 \] \[ 5N^2 - 125N + 720 = 0 \] ### Step 7: Dividing by 5 To simplify, divide the entire equation by 5: \[ N^2 - 25N + 144 = 0 \] ### Step 8: Solving the Quadratic Equation Using the quadratic formula \( N = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \): Here, \( a = 1, b = -25, c = 144 \): \[ N = \frac{25 \pm \sqrt{(-25)^2 - 4 \times 1 \times 144}}{2 \times 1} \] \[ N = \frac{25 \pm \sqrt{625 - 576}}{2} \] \[ N = \frac{25 \pm \sqrt{49}}{2} \] \[ N = \frac{25 \pm 7}{2} \] Calculating the two possible values: 1. \( N = \frac{32}{2} = 16 \) 2. \( N = \frac{18}{2} = 9 \) ### Conclusion for Statement 1 Since we are looking for a convex polygon with angles in A.P. and we found \( N = 16 \), Statement 1 is **True**. ### Step 9: Validating Statement 2 Statement 2 states that the sum of the angles of a polygon with \( N \) sides is given by \( (N - 2) \times 180° \). This is a well-known formula in geometry for polygons, hence Statement 2 is also **True**. ### Final Answer Both statements are true. ---
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