What property could be used to solve 6x=72
2 answers:
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Answer:
Step-by-step explanation:
- A circle's equation consist on the following expression:
, where r is the magnitude of the radio, and (a,b) are the coordenates of the center of the circle.
- In this case, a=2 and b= - 3, because the circle is centered in (x,y)=(2, - 3).
- The radio, which is the distance between the center of the radio to any point in its border, equals r=2 (because of the scale of the graphic, in this case two squares of the grid equal 2 units, then r=2).
- Finally, using the previous information to replace in the equation
, where the fact that r=2 and
was used.
Answer:
r = (ab)/(a+b)
Step-by-step explanation:
Consider the attached sketch. The diagram shows base b at the bottom and base a at the top. The height of the trapezoid must be twice the radius. The point where the slant side of the trapezoid is tangent to the inscribed circle divides that slant side into two parts: lengths (a-r) and (b-r). The sum of these lengths is the length of the slant side, which is the hypotenuse of a right triangle with one leg equal to 2r and the other leg equal to (b-a).
Using the Pythagorean theorem, we can write the relation ...
((a-r) +(b-r))^2 = (2r)^2 +(b -a)^2
a^2 +2ab +b^2 -4r(a+b) +4r^2 = 4r^2 +b^2 -2ab +a^2
-4r(a+b) = -4ab . . . . . . . . subtract common terms from both sides, also -2ab
r = ab/(a+b) . . . . . . . . . divide by the coefficient of r
The radius of the inscribed circle in a right trapezoid is r = ab/(a+b).
_____
The graph in the second attachment shows a trapezoid with the radius calculated as above.
