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Permutations and Combinations
Geometry, Combinatorics
jee_main_2026_april_4_shift_2
Grade 12
Question:
The number of diagonals in a pentagon is D. If each diagonal is extended to form a line, the total number of lines formed including the sides is L. Find L - D.
Step-by-Step Solution
Key Concept: Diagonals formula n(n-3)/2; total lines = sides + diagonals.
Step 1: Diagonals D = 5(5-3)/2 = 5. Step 2: Sides = 5. Step 3: Total lines L = 5 + 5 = 10. Step 4: L - D = 10 - 5 = 5.
Correct Answer:5
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