If the length of AO is double the length of CO, the length of BO is?
1 answer:
BO is double that of DO. In other words, BO is two times longer than DO. The answer is choice B
For example, if DO were 3 units long, then BO would be 6 units long (2*3 = 6). This works because the triangles DCO and BAO are similar triangles. The corresponding sides are in the same ratio or proportion to one another. The larger triangle (BAO) has sides that are twice as long as the smaller triangle's (DCO) corresponding sides.
Side note: we can prove the triangles to be similar using the AA (angle angle) similarity theorem. The first pair of angles are the vertical angles DOC and BOA which are congruent to each other.The second pair is CDB and ABD which are congruent by the alternate interior angle theorem. Check out the attached image for a visual.
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Let's look at an example:
2.24 x 21.6
Do normal multiplication and get
48384 This is not correct, until we put the decimals in. To know how to do this, count the number of decimal spaces from the factors. In 2.24, there are 2, because .24. In 21.6 there are 1 because of .6. This mean three places, so 48384 becomes
48.384
~theLocoCoco
They forget to say "not to scale". I'm guessing this is trig because I don't see another way to do it.
Let's consider x=chord PQ first. By the Law of Cosines
We have an isosceles triangle formed by two radii of 9 cm and x=PQ. By the Law of Cosines again,
The area of the circle is the fraction given by the angle,
Answer: 24.7 sq cm