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80 km / hr   x   1 hr / 60 min  x  18 min   =   24 km

Let's look at this again

The exterior angles sum to 360

The smallest exterior angle will be supplemental to the largest  interior angle

So....the smallestt exterior angle is  (2/9)(360) = 80°

So...the largest interior angle = 180 - 80   =  100°  = y

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180°  x  pi / 180    =    pi  rads

Minor arc AB   =  360 - 286  =  74°

The minute hand moves 2pi/60 =  pi/30 rads  every minute  = 6° every minute

The hour hand moves pi/6 rads every hour so it moves pi/360 rads every miniute = .5° every  minute

So...in 18 minutes....

The minute hand moves  18* 6 = 108°

And the hour hand moves   .5 * 18  =  9°

So....

The minute hand is    108 - ( 9 + 20)  =  108 - 29 = 79°  ahead of the hour hand after 18 mnutes

The ratio of the circumference of a circle to its diameter is same for every circle.

To see why this is true.....note that the circumference = 2pi^r = (2r)*pi  = (diameter)* pi

So

circumference / diameter  =   (diameter) * pi  / diameter  =   pi    (which is a constant)

Dilate circle Q by a scale factor of p/q.

To see this.....let the radius of P = 6   and the radius of Q = 3

Then.....dilating Q  we  get the new radius of   3 * 6/3  =  6 = the same radius as P