In the given diagram, $O$ is the center of the circle. We are given that $\angle SQR = 60^{\circ}$, $\angle SPR = y$, and $\angle SOR = 3x$. We need to find the value of $x + y$.

GeometryCirclesAnglesInscribed AnglesCentral AnglesQuadrilaterals
2025/4/29

1. Problem Description

In the given diagram, OO is the center of the circle. We are given that SQR=60\angle SQR = 60^{\circ}, SPR=y\angle SPR = y, and SOR=3x\angle SOR = 3x. We need to find the value of x+yx + y.

2. Solution Steps

Since OO is the center of the circle, SOR\angle SOR is the central angle subtended by the arc SRSR. SPR\angle SPR is an inscribed angle subtended by the same arc SRSR.
We know that the inscribed angle is half of the central angle. Therefore, we have:
y=12SORy = \frac{1}{2} \angle SOR
y=12(3x)y = \frac{1}{2} (3x)
y=32xy = \frac{3}{2}x
Also, we know that the angle at the center is twice the angle at the circumference subtended by the same arc. Therefore:
POR=2PSR\angle POR = 2\angle PSR
Since OS=OROS=OR (radii of the same circle), SOR\triangle SOR is an isosceles triangle. Thus OSR=ORS\angle OSR = \angle ORS.
Also, we have SOR+OSR+ORS=180\angle SOR + \angle OSR + \angle ORS = 180^{\circ}.
Since SOR=3x\angle SOR = 3x, we have 3x+OSR+ORS=1803x + \angle OSR + \angle ORS = 180^{\circ}.
Since OSR=ORS\angle OSR = \angle ORS, we have 3x+2ORS=1803x + 2\angle ORS = 180^{\circ}.
ORS=1803x2=9032x\angle ORS = \frac{180 - 3x}{2} = 90 - \frac{3}{2}x.
We are given that SQR=60\angle SQR = 60^{\circ}. Also, SQR\angle SQR and SPR\angle SPR subtend the same arc SR. Thus y=SPRy = \angle SPR. Since y=12(3x)y = \frac{1}{2} (3x), 2y=3x2y = 3x.
Now consider the quadrilateral PSQRPSQR.
The angles PSR\angle PSR and PQR\angle PQR are subtended by the same chord PRPR.
Also PSR+PRQ=180(QPS+SQR)\angle PSR + \angle PRQ = 180^{\circ} - (\angle QPS + \angle SQR)
We are given SQR=60\angle SQR = 60^{\circ}. Also OS=OROS = OR, which implies triangle SORSOR is an isosceles triangle. Therefore OSR=ORS=(1803x)/2=901.5x\angle OSR = \angle ORS = (180^{\circ}-3x)/2 = 90-1.5x. Similarly OP=OQOP=OQ, which means OPQ=OQP\angle OPQ = \angle OQP. We are given SQR=60\angle SQR = 60^{\circ}.
Consider the angle SOR=3x\angle SOR=3x. The inscribed angle that subtends the same arc is yy. 2y=3x2y = 3x, so y=32xy = \frac{3}{2} x.
In quadrilateral PSQRPSQR, SPR=y\angle SPR = y and SQR=60\angle SQR = 60^{\circ}. The sum of the angles of quadrilateral is
3
6

0. We can consider the $\angle SOR$. $\angle SOR = 2 \angle SQR$.

SPR=SOR2=3x2=y\angle SPR = \frac{\angle SOR}{2} = \frac{3x}{2} = y.
Since the total angles in the quadrilateral PSQRPSQR add up to 360360^{\circ},
SQR=60\angle SQR = 60^{\circ}
SPR=y\angle SPR = y
PSR=a\angle PSR = a
PQR=b\angle PQR = b
y+60+a+b=360y + 60 + a + b = 360
a+b=300ya + b = 300 - y.
Consider triangle OSROSR. OS=OROS=OR and SOR=3x\angle SOR = 3x. Therefore OSR=ORS\angle OSR = \angle ORS.
OSR=ORS=(1803x)/2=901.5x\angle OSR = \angle ORS = (180-3x)/2 = 90 - 1.5 x.
We are given SQR=60\angle SQR = 60.
We also have inscribed angle yy corresponds to 3x3x at center.
    2y=3x\implies 2y = 3x
Since the arc SR subtends angle SQR=60SQR = 60 at QQ, we have SOR=2SQR=120\angle SOR= 2\angle SQR=120^{\circ}.
Then 3x=1203x=120^{\circ}, x=40x=40^{\circ}. Since 2y=3x2y=3x, we have 2y=3(40)=1202y=3(40)=120^{\circ}. Therefore y=60y=60^{\circ}.
Therefore x+y=40+60=100x+y = 40^{\circ}+60^{\circ}=100^{\circ}.

3. Final Answer

100°

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