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I : If x cos theta = y cos (120^@ + the...

I : If ` x cos theta = y cos (120^@ + theta ) = z cos ( theta + 240^(@)) ` then xy+ yz+ zx=1
II : ` cos alpha + cos (120^(@) + alpha ) + cos (120^@ - alpha ) =0`

A

only I is true

B

only II is true

C

both I & II are true

D

neither I nor II are true

Text Solution

Verified by Experts

The correct Answer is:
B
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