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Problem 5 - Entrance Test

If tan A + cot A = 2, then find the value of tan² A + cot² A.

Correct: C

Given tan A + cot A = 2. Square both sides of the equation: (tan A + cot A)² = 2². Expand the left side: tan² A + cot² A + 2(tan A)(cot A) = 4. We know that tan A = 1/cot A, so tan A * cot A = 1. Substitute this into the equation: tan² A + cot² A + 2(1) = 4. So, tan² A + cot² A + 2 = 4. Subtract 2 from both sides: tan² A + cot² A = 4 - 2 = 2.