Find the radius of the circle circumscribed around an equilateral triangle, if the radius of the circle inscribed into this triangle is 10 cm

  20 cm

Step-by-step explanation:

For an equilateral triangle the radius of the inscribed circle is half the radius of the circumscribed circle. The radius of the circumscribed circle is ...

  2×10 cm = 20 cm.

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The center of both circles is the centroid of the triangle, which is 1/3 of the distance from a side to the opposite vertex. That is, the centroid-vertex distance is twice the centroid-side distance. The latter is the radius of the inscribed circle; the former is the radius of the circumscribed circle.

( - 4 , -7 )

all the lines must parallel  

step-by-step explanation:

coordinates of c = ( - 1 , 2 )

3 units left = ( -4 , 2 )

9 units down = ( - 4 , 11 )