The inside perimetre of a running track is 400m. The length of each of the straight portion is 90m and the ends are semi-circles. If the track is everywhere 14m wide, find the area of the track. Also find the length of the outer running track.

Dear Student!

Let the radius of the inner semi-circular ends be *r *m.

Given, Inner perimeter of running track = 400 m

Circumference of the semi-circle, BC and AD =

∴

Area of the track

= Area of the ring AEHD + Area of rectangle ABFE + Area of ring BFGC + Area of rectangle CDHG.

= 3696 m^{2} + 2520 m^{2}

= 6216 m^{2}

∴ The area of the track is 6216 m^{2}.

Length of the outer running track

= EF + Length of arc, FG + GH + Length is arc, HE

= 180m + 308m

= 488m

∴ The length of the outer running track is 488 m.

Cheers!

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