The length of side AB of quadrilateral ABCD having CD = 4, BC + AD = 10 units and inradius as a finite nonzero number will be:

Explanation

Let the incircle touches the quadrilateral `ABCD` at points `P,Q,R and S`.

Please refer to video for the diagram.

We know tangents from a common point outside a circle is alays equal.

`:. DP = DS->(1)`

`CS = CR = CD-DS = 4-DS->(2)` (As CD = 4)

`BQ = BR->(3)`

`AQ = AP->(4)`

Also, we are given,

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