00:00Here you have my question, cos alpha plus cos beta is equal to 0
00:04or sin alpha plus sin beta is also equal to 0
00:09Then what is the value of cos 2 alpha plus cos 2 beta plus 2 cos alpha plus beta
00:16So cos 2 alpha identity is cos square alpha minus sin square alpha
00:21So we will put it in that way
00:23cos square alpha minus sin square alpha
00:28Same in the place of cos 2 beta plus cos square beta minus sin square beta
00:38We are replacing it by identity in cos beta and sin beta form
00:42Plus 2 cos alpha beta cos A plus B identity is 2 cos A cos B
00:49Which become cos alpha cos beta minus 2 is multiplied to this one also
00:56So 2 sin alpha sin beta minus 2 sin alpha sin beta
01:06Now if we square this, so this becomes cos alpha plus cos, no need to do that
01:16So we can write it cos alpha plus cos square beta plus 2 cos alpha 2 cos beta
01:23So we can see this is cos alpha plus cos beta whole square
01:32Cos square alpha plus cos square beta plus 2 cos alpha beta
01:36Cos alpha plus beta value is 0, so 0 square is also 0
01:42In the same way, in the same way, in the same way, in the same way, take minus common
01:45So it becomes sin square alpha plus sin square beta
01:50So it becomes sin square alpha plus sin beta
01:59So we can see inside minus also 0 minus sin alpha plus sin beta whole square
02:10Here we can see sin alpha plus sin beta is equal to 0
02:15So 0 whole square is also equal to 0
02:18So 0 minus 0 is 0
02:21So our final answer will be 0
02:23So we can see if we can see if we can see if we can see if we can see
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02:24if we can see if we can see if we can see if we can see if we can see
02:24if we can see if we can see if we can see if we can see if we can see
02:24if we can see if we can see if we can see if we can see if we can see
02:24if we can see if we can see if we can see if we can see if we can see
02:24if we can see if we can see if we can see if we can see if we can see
02:24if
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