JEE MAIN - Mathematics (2003 - No. 27)
The vectors $$\overrightarrow {AB} = 3\widehat i + 4\widehat k\,\,\& \,\,\overrightarrow {AC} = 5\widehat i - 2\widehat j + 4\widehat k$$ are the sides of triangle $$ABC.$$ The length of the median through $$A$$ is :
$$\sqrt {288} $$
$$\sqrt {18} $$
$$\sqrt {72} $$
$$\sqrt {33} $$
Explanation
$$PV\,\,$$ of $$\,\,\overrightarrow {AD} $$ $$ = {{\left( {3 + 5} \right)i + \left( {0 - 2} \right)j + \left( {4 + 4} \right)k} \over 2}$$
$$ = 4i - j + 4k\,\,$$
or $$\,\,\,\left| {\overrightarrow {AD} } \right| = \sqrt {16 + 16 + 1} = \sqrt {33} $$
Comments (0)
