Find the position vector of a point A in space such that is inclined at 60° to and at 45° to and = 10 units.

We are given that,

is inclined at 60° to and at 45° to .



We need to find the position vector of point A in space.


That is,


Position vector of A =


So, we need to find .


We know that, space contains three axes, namely, X, Y and Z.


Let OA be inclined at angle α with OZ.


And we know that direction cosines are associated by the relation,


l2 + m2 + n2 = 1 …(i)


And here, direction cosines are cosines of the angles inclined by on , and . So,


l = cos 60°


m = cos 45°


n = cos α


Substituting these values of l, m and n in equation (i), we get


(cos 60°)2 + (cos 45°)2 + (cos α)2 = 1


We know the values of cos 60° and cos 45°.


That is,




We get,









So is given as,


…(ii)


We have,





Putting these values of l, m and n in equation (ii), we get



Also, put .







Thus, position vector of point A in space is .


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