Find the values of p so that the lines are at right angles.

For any two lines to be at right angles, the angle between them should be θ = 90°.

⇒ a_{1}a_{2} + b_{1}b_{2} + c_{1}c_{2} = 0, where a_{1}, b_{1}, c_{1} and a_{2}, b_{2}, c_{2} are the direction ratios of two lines.

The standard form of a pair of Cartesian lines is:

and …(i)

Now, first we rewrite the given equations according to the standard form, i.e.

and , i.e.

and …(ii)

Now, comparing (i) and (ii), we get

and

Now, as both the lines are at right angles,

so a_{1}a_{2} + b_{1}b_{2} + c_{1}c_{2} = 0

⇒

⇒

⇒

⇒

⇒ 11p = 70

⇒

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