If a circle has a diameter of 8cm, what is the radius of this circle?
1 answer:
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Since ABCD is a parallelogram, the opposite sides will be parallel and equal,
Consider that AC acts as a transversal to the parallel lines AB and CD, so we can write,
So by the ASA criteria, the triangle AED is congruent to the triangle CEB,
Then the corresponding parts of the triangles will be equal,
Hence Proved.
Answer:
OK, lets start by drawing a basic graph (the first one) so we can visualize.
We already know that the y coordinate of the circle's center is .
We know that the circle is tangent to the axis at
That means the x coordinate of the center has to be , as the tangent is a point on the edge of the circle that touches a line at exactly one point.
The radius is the distance from the center of the circle to its edge. We know the center's location now, it is and a point on the edge of the circle (the tangent point) which is
. so the distance between the points is 4 which is the radius (you can use the distance formula, but it's quite oblivious.)
We can imagine the circle should look like this (the second one):
Now we can piece together an equation
The equation of a circle is where
is the center and
is the radius. When we put the numbers in: we get
which can be simplified into
which is the answer.
Step-by-step explanation:
