CSEC Additional Mathematics · 2013 · Paper 1 · Question Q26
The position vectors of A and B relative to an origin O are \begin{pmatrix} 2 \\ 5 \end{pmatrix} and \begin{pmatrix} 3 \\ -1 \end{pmatrix} respectively. The acute angle AOB is given by
- (A)
\cos^{-1}\left(\frac{1}{\sqrt{290}}\right) - (B)
\cos^{-1}\left(\frac{11}{\sqrt{290}}\right) - (C)
\cos^{-1}\left(\frac{\sqrt{11}}{\sqrt{290}}\right) - (D)
\cos^{-1}\left(\frac{-1}{290}\right)
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