The vectors a̅, b̅, c̅ and d̅ are such that a̅ × b̅ = c̅ × d̅ and a̅ × c̅ = b̅ × d̅. Which of the following is/are correct ?

1. (a̅ – d̅) × (b̅ – c̅) = 0̅

2. (a̅ × b̅) × (c̅ × d̅) = 0̅

Select the correct answer using the code given below :

Mathematics 2015 NDA Mathematics 2015 NDA 2015

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