Soh Lih Fei's answer to Shermel ET's Secondary 3 E Maths question.
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We are given the length of OA and BC, hence, to find the perimeter of the shaded region we need to find the curved circumference of the semicircle OC and the quadrant OAB.
To find curved circumference of semicircle OC, note that we use the formula pie x r (because semicircle is half of circle). The radius of the semicircle is half of OC, which is 0.5 x 3cm= 1.5cm.
To find the curved circumference of quadrant OAB, we use the formula 0.5 x pie x r (because quadrant is a quarter of a circle) . The radius of the quadrant is given as 6cm.
Sub in the values into the formula to get the curved circumferences of semicircle and quadrant, then add up the sides (OA+BC) to get the perimeter of the shaded region.
To find curved circumference of semicircle OC, note that we use the formula pie x r (because semicircle is half of circle). The radius of the semicircle is half of OC, which is 0.5 x 3cm= 1.5cm.
To find the curved circumference of quadrant OAB, we use the formula 0.5 x pie x r (because quadrant is a quarter of a circle) . The radius of the quadrant is given as 6cm.
Sub in the values into the formula to get the curved circumferences of semicircle and quadrant, then add up the sides (OA+BC) to get the perimeter of the shaded region.
Date Posted:
6 years ago
thank you :)
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