A) \[\frac{ab+cd}{\sqrt{{{a}^{2}}+{{b}^{2}}}\sqrt{{{c}^{2}}+{{d}^{2}}}}\]
B) \[\frac{ab}{\sqrt{{{a}^{2}}+{{b}^{2}}}}+\frac{bd}{\sqrt{{{c}^{2}}+{{d}^{2}}}}\]
C) \[\frac{ac+bd}{\sqrt{{{a}^{2}}+{{b}^{2}}}\sqrt{{{c}^{2}}+{{d}^{2}}}}\]
D) \[\frac{ab-cd}{\sqrt{{{a}^{2}}+{{b}^{2}}}\sqrt{{{c}^{2}}+{{d}^{2}}}}\]
E) \[\frac{ab-cd}{\sqrt{{{a}^{2}}+{{b}^{2}}}\sqrt{{{c}^{2}}+{{d}^{2}}}}\]
Correct Answer: C
Solution :
We know that, \[\cos A=\frac{{{b}^{2}}+{{c}^{2}}-{{a}^{2}}}{2bc}\]You need to login to perform this action.
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