Circle J is inscribed in isosceles trapezoid ABCD, as shown. Points E, F, G, and H are points of tangency. The length of AB is 10 cm. The length of DC is 20 cm. What is the length, in cm, of BC?

15cm

Step-by-step explanation:

Theorem: All tangents to a circle from the same point are equal.

Sine E, F, G and H are points of Tangency, by the theorem above:

The diameter line EC divides the Isosceles Trapezoid into two equal parts.

Therefore:

We then have by the equality above that:

BC=BF+FC

=5+10

=15cm

the entire expression should be subtracted from 30. to subtract the quantity, distribute the negative sign, which changes the signs on the terms. so, the –2 changes to positive and gets added to 30 instead of subtracted from it.

hope this ! ^w^

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