Directions Cosine and Ratios of Vector
NEET Test Series from KOTA - 10 Papers In MS WORD WhatsApp Here
Vector Algebra

87878 If \(a, b, c\) are vectors of equal magnitude such that \((a, b)=\alpha,(b, c)=\beta,(c, a)=\gamma\), then the minimum value of \(\cos \alpha+\cos \beta+\cos \gamma\) is

1 \(\frac{3}{2}\)
2 \(-\frac{3}{2}\)
3 \(\frac{1}{2}\)
4 \(-\frac{1}{2}\)
Vector Algebra

87879 Let ' \(O\) ' be the origin and ' \(\mathrm{P}\) ' be a point which is at a distance of 3 units from the origin. If the direction ratios of \(\overline{\mathrm{OP}}\) are \((1,-2,-2)\) then the coordinates of ' \(P\) ' are

1 \((1,-2,-2)\)
2 \((3,-6,-6)\)
3 \(\left(\frac{1}{3}, \frac{-2}{3}, \frac{-2}{3}\right)\)
4 \(\left(\frac{1}{9}, \frac{-2}{9}, \frac{-2}{9}\right)\)
Vector Algebra

87881 If \(l_1, \mathbf{m}_1, \mathbf{n}_1\) and \(l_2, \mathbf{m}_2, \mathbf{n}_2\) are direction cosines of \(\overline{\mathrm{OA}}\) and \(\overline{\mathrm{OB}}\) such that \(\angle \mathrm{AOB}=\theta\), where \(O\) is the origin, then the direction cosines of the internal angular bisector of \(\angle \mathrm{AOB}\) are

1 \(\frac{l_1+l_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{m}_1+\mathrm{m}_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{n}_1+\mathrm{n}_2}{2 \sin \frac{\theta}{2}}\)
2 \(\frac{l_1-l_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{m}_1-\mathrm{m}_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{n}_1-\mathrm{n}_2}{2 \cos \frac{\theta}{2}}\)
3 \(\frac{l_1-l_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{m}_1-\mathrm{m}_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{n}_1-\mathrm{n}_2}{2 \sin \frac{\theta}{2}}\)
4 \(\frac{l_1+l_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{m}_1+\mathrm{m}_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{n}_1+\mathrm{n}_2}{2 \cos \frac{\theta}{2}}\)
Vector Algebra

87882 If \(\bar{a}=\bar{i}+2 \bar{j}+3 \bar{k}, \bar{b}=-\bar{i}+2 \bar{j}+\bar{k}, \bar{c}=\bar{i}+2 \bar{j}-2 \bar{k}, n\) is perpendicular to both \(a\) and \(b\) and \(\theta\) is angle between \(\mathrm{c}\) and \(\mathrm{n}\) then \(\sin \theta=\)

1 \(\sqrt{\frac{2}{3}}\)
2 \(\frac{\sqrt{2}}{3 \sqrt{3}}\)
3 \(\frac{2}{\sqrt{3}}\)
4 \(\frac{\sqrt{3}}{2}\)
Vector Algebra

87878 If \(a, b, c\) are vectors of equal magnitude such that \((a, b)=\alpha,(b, c)=\beta,(c, a)=\gamma\), then the minimum value of \(\cos \alpha+\cos \beta+\cos \gamma\) is

1 \(\frac{3}{2}\)
2 \(-\frac{3}{2}\)
3 \(\frac{1}{2}\)
4 \(-\frac{1}{2}\)
Vector Algebra

87879 Let ' \(O\) ' be the origin and ' \(\mathrm{P}\) ' be a point which is at a distance of 3 units from the origin. If the direction ratios of \(\overline{\mathrm{OP}}\) are \((1,-2,-2)\) then the coordinates of ' \(P\) ' are

1 \((1,-2,-2)\)
2 \((3,-6,-6)\)
3 \(\left(\frac{1}{3}, \frac{-2}{3}, \frac{-2}{3}\right)\)
4 \(\left(\frac{1}{9}, \frac{-2}{9}, \frac{-2}{9}\right)\)
Vector Algebra

87881 If \(l_1, \mathbf{m}_1, \mathbf{n}_1\) and \(l_2, \mathbf{m}_2, \mathbf{n}_2\) are direction cosines of \(\overline{\mathrm{OA}}\) and \(\overline{\mathrm{OB}}\) such that \(\angle \mathrm{AOB}=\theta\), where \(O\) is the origin, then the direction cosines of the internal angular bisector of \(\angle \mathrm{AOB}\) are

1 \(\frac{l_1+l_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{m}_1+\mathrm{m}_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{n}_1+\mathrm{n}_2}{2 \sin \frac{\theta}{2}}\)
2 \(\frac{l_1-l_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{m}_1-\mathrm{m}_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{n}_1-\mathrm{n}_2}{2 \cos \frac{\theta}{2}}\)
3 \(\frac{l_1-l_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{m}_1-\mathrm{m}_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{n}_1-\mathrm{n}_2}{2 \sin \frac{\theta}{2}}\)
4 \(\frac{l_1+l_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{m}_1+\mathrm{m}_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{n}_1+\mathrm{n}_2}{2 \cos \frac{\theta}{2}}\)
Vector Algebra

87882 If \(\bar{a}=\bar{i}+2 \bar{j}+3 \bar{k}, \bar{b}=-\bar{i}+2 \bar{j}+\bar{k}, \bar{c}=\bar{i}+2 \bar{j}-2 \bar{k}, n\) is perpendicular to both \(a\) and \(b\) and \(\theta\) is angle between \(\mathrm{c}\) and \(\mathrm{n}\) then \(\sin \theta=\)

1 \(\sqrt{\frac{2}{3}}\)
2 \(\frac{\sqrt{2}}{3 \sqrt{3}}\)
3 \(\frac{2}{\sqrt{3}}\)
4 \(\frac{\sqrt{3}}{2}\)
Vector Algebra

87878 If \(a, b, c\) are vectors of equal magnitude such that \((a, b)=\alpha,(b, c)=\beta,(c, a)=\gamma\), then the minimum value of \(\cos \alpha+\cos \beta+\cos \gamma\) is

1 \(\frac{3}{2}\)
2 \(-\frac{3}{2}\)
3 \(\frac{1}{2}\)
4 \(-\frac{1}{2}\)
Vector Algebra

87879 Let ' \(O\) ' be the origin and ' \(\mathrm{P}\) ' be a point which is at a distance of 3 units from the origin. If the direction ratios of \(\overline{\mathrm{OP}}\) are \((1,-2,-2)\) then the coordinates of ' \(P\) ' are

1 \((1,-2,-2)\)
2 \((3,-6,-6)\)
3 \(\left(\frac{1}{3}, \frac{-2}{3}, \frac{-2}{3}\right)\)
4 \(\left(\frac{1}{9}, \frac{-2}{9}, \frac{-2}{9}\right)\)
Vector Algebra

87881 If \(l_1, \mathbf{m}_1, \mathbf{n}_1\) and \(l_2, \mathbf{m}_2, \mathbf{n}_2\) are direction cosines of \(\overline{\mathrm{OA}}\) and \(\overline{\mathrm{OB}}\) such that \(\angle \mathrm{AOB}=\theta\), where \(O\) is the origin, then the direction cosines of the internal angular bisector of \(\angle \mathrm{AOB}\) are

1 \(\frac{l_1+l_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{m}_1+\mathrm{m}_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{n}_1+\mathrm{n}_2}{2 \sin \frac{\theta}{2}}\)
2 \(\frac{l_1-l_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{m}_1-\mathrm{m}_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{n}_1-\mathrm{n}_2}{2 \cos \frac{\theta}{2}}\)
3 \(\frac{l_1-l_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{m}_1-\mathrm{m}_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{n}_1-\mathrm{n}_2}{2 \sin \frac{\theta}{2}}\)
4 \(\frac{l_1+l_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{m}_1+\mathrm{m}_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{n}_1+\mathrm{n}_2}{2 \cos \frac{\theta}{2}}\)
Vector Algebra

87882 If \(\bar{a}=\bar{i}+2 \bar{j}+3 \bar{k}, \bar{b}=-\bar{i}+2 \bar{j}+\bar{k}, \bar{c}=\bar{i}+2 \bar{j}-2 \bar{k}, n\) is perpendicular to both \(a\) and \(b\) and \(\theta\) is angle between \(\mathrm{c}\) and \(\mathrm{n}\) then \(\sin \theta=\)

1 \(\sqrt{\frac{2}{3}}\)
2 \(\frac{\sqrt{2}}{3 \sqrt{3}}\)
3 \(\frac{2}{\sqrt{3}}\)
4 \(\frac{\sqrt{3}}{2}\)
NEET Test Series from KOTA - 10 Papers In MS WORD WhatsApp Here
Vector Algebra

87878 If \(a, b, c\) are vectors of equal magnitude such that \((a, b)=\alpha,(b, c)=\beta,(c, a)=\gamma\), then the minimum value of \(\cos \alpha+\cos \beta+\cos \gamma\) is

1 \(\frac{3}{2}\)
2 \(-\frac{3}{2}\)
3 \(\frac{1}{2}\)
4 \(-\frac{1}{2}\)
Vector Algebra

87879 Let ' \(O\) ' be the origin and ' \(\mathrm{P}\) ' be a point which is at a distance of 3 units from the origin. If the direction ratios of \(\overline{\mathrm{OP}}\) are \((1,-2,-2)\) then the coordinates of ' \(P\) ' are

1 \((1,-2,-2)\)
2 \((3,-6,-6)\)
3 \(\left(\frac{1}{3}, \frac{-2}{3}, \frac{-2}{3}\right)\)
4 \(\left(\frac{1}{9}, \frac{-2}{9}, \frac{-2}{9}\right)\)
Vector Algebra

87881 If \(l_1, \mathbf{m}_1, \mathbf{n}_1\) and \(l_2, \mathbf{m}_2, \mathbf{n}_2\) are direction cosines of \(\overline{\mathrm{OA}}\) and \(\overline{\mathrm{OB}}\) such that \(\angle \mathrm{AOB}=\theta\), where \(O\) is the origin, then the direction cosines of the internal angular bisector of \(\angle \mathrm{AOB}\) are

1 \(\frac{l_1+l_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{m}_1+\mathrm{m}_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{n}_1+\mathrm{n}_2}{2 \sin \frac{\theta}{2}}\)
2 \(\frac{l_1-l_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{m}_1-\mathrm{m}_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{n}_1-\mathrm{n}_2}{2 \cos \frac{\theta}{2}}\)
3 \(\frac{l_1-l_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{m}_1-\mathrm{m}_2}{2 \sin \frac{\theta}{2}}, \frac{\mathrm{n}_1-\mathrm{n}_2}{2 \sin \frac{\theta}{2}}\)
4 \(\frac{l_1+l_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{m}_1+\mathrm{m}_2}{2 \cos \frac{\theta}{2}}, \frac{\mathrm{n}_1+\mathrm{n}_2}{2 \cos \frac{\theta}{2}}\)
Vector Algebra

87882 If \(\bar{a}=\bar{i}+2 \bar{j}+3 \bar{k}, \bar{b}=-\bar{i}+2 \bar{j}+\bar{k}, \bar{c}=\bar{i}+2 \bar{j}-2 \bar{k}, n\) is perpendicular to both \(a\) and \(b\) and \(\theta\) is angle between \(\mathrm{c}\) and \(\mathrm{n}\) then \(\sin \theta=\)

1 \(\sqrt{\frac{2}{3}}\)
2 \(\frac{\sqrt{2}}{3 \sqrt{3}}\)
3 \(\frac{2}{\sqrt{3}}\)
4 \(\frac{\sqrt{3}}{2}\)