GATE | GATE CS 1996 | Question 31

The matrices commute under multiplication (A) if a = b or Θ = nπ, n an integer (B) always (C) never (D) if a cosΘ = b sin Θ
Answer:(A)
Explanation: For Commutativity, AB = BA Since AB = BA On Comparing corresponding elements we get- The above holds when either, or which is true when . Therefore option (A) is correct. This explanation is provided by Chirag Manwani.
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