The first step to the proof is ∠QRS + ∠STQ = 180°
What is a cyclic Quadrilateral?
A cyclic quadrilateral is a quadrilateral circumscribed by a circle in which all the vertices of the quadrilateral touch the circle.
Analysis:
Join line Qx and Sx together.
2∠QRS = reflex ∠QxS ( twice angle at the circumference is that at center)
2∠STQ = ∠QxS( twice angle at circumference is that at the center)
Also ∠QXS + reflex ∠QXS = 360(angle at a point)
2∠QRS + 2∠STQ = 360
2(∠QRS + ∠STQ) = 360
∠QRS + ∠STQ = 180°
In conclusion, ∠QRS + ∠STQ = 180°
Learn more about cyclic quadrilateral: brainly.com/question/24142962
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