The length of the third side of the quadrilateral is 7.5 cm.
A quadrilateral is a polygon that has four sides and four angles. The sum of interior angles in a quadrilateral is 360°. Types of quadrilateral are square, rectangle, rhombus, kite and so on.
Let x represent the length of the third side, hence:
x = 5 + (5 * sin(20)) + (5 * sin(10)) = 7.5 cm
The length of the third side of the quadrilateral is 7.5 cm.
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