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Question
The value of sin ( \[{45}^° + \theta) - \cos ( {45}^°- \theta)\] is equal to
Options
2 cos \[\theta\]
0
2 sin \[\theta\]
1
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Solution
We know that,
\[\sin\left( 90 - \theta \right) = \cos\theta\]
So,
\[\sin\left( 45°+ \theta \right) = \cos\left[ 90 - \left( 45° + \theta \right) \right] = \cos\left( 45° - \theta \right)\]
\[\therefore \sin\left( 45°+ \theta \right) - \cos\left( 45°- \theta \right)\]
\[ = \cos\left( 45° - \theta \right) - \cos\left( 45° - \theta \right)\]
\[ = 0\]
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