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Mathematics 16 Online
OpenStudy (anonymous):

Help. diagram shows a circle PQRS with centre O and radius 10cm. PQTS is a sector of a circle with centre P that INSCRIBED in the circle PQRS. Calculate the length of arc QTS.

OpenStudy (anonymous):

OpenStudy (anonymous):

first calculate angle QOS radius = 10 cm arc length = angle QOS (in Radians) * radius

OpenStudy (anonymous):

If i do it like that. I ll get the length of arc QRS??

OpenStudy (anonymous):

i think you can get arc length QTS radius = 20 cm angle QPS = pi/3 arc length = angle QPS (in Radians) * radius try to solve like this

OpenStudy (calculusfunctions):

@uzumakhi, is partially correct. arc length equals to the product of the central angle in radians and the radius of the circle.

OpenStudy (anonymous):

QOP AND OSP SIMILAR

OpenStudy (anonymous):

when i see diagram carefully i come to know that arc QTS is arc of circle with center P therefore its angle is 60 degree and radius 20 cm

OpenStudy (anonymous):

i am not sure about its radius

OpenStudy (anonymous):

\[PQ = 2r \sin(\frac{ \theta }{ 2 }) \] where theta is 120 degree

OpenStudy (anonymous):

10 x radians (120 degrees)

OpenStudy (anonymous):

Looking at POS, then radius PS is 2* 10 cos 30 = 10 sqrt 3 ?

OpenStudy (anonymous):

PQS may not be equilateral triangle

OpenStudy (anonymous):

radius = 17.3 cm angle QPS = 60 degree arc length = angle QPS (in Radians) * radius try to solve like this

OpenStudy (anonymous):

@uzumaki How do u know that the radius is 17.3 ?

OpenStudy (anonymous):

10 sqrt 3

OpenStudy (anonymous):

\(\triangle OSP \cong \triangle OQP\) by SSS

OpenStudy (anonymous):

PQ=2rsin(θ/2)

OpenStudy (anonymous):

60/360 = QS/(2pi 10 sqrt 3)

OpenStudy (anonymous):

this PQ is Radius

OpenStudy (anonymous):

PS = 20 cos 30

OpenStudy (anonymous):

length of QTS = \(\frac{rad(60 degrees)}{20 cos 30}\)

OpenStudy (anonymous):

THANK YOU . I get it now. So the answer is 18.14 cm. is it?

OpenStudy (anonymous):

yes you are right

OpenStudy (anonymous):

i have th eformula wrong there, length of QTS = \(rad(60 degrees) \times 20 cos 30 \) = 18.14

OpenStudy (anonymous):

|dw:1349776058346:dw|

OpenStudy (anonymous):

QTS=18.14CM

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