In Friday's class, we started off by doing Quiz Number 2. We had thirty minutes or so to finish it. Then time was up! We passed them up so Mr. K could pass them out so we could go over them and correct them.

Here is question one! We had to find the arcs. of AB, BC, CD and AD.













It starts us off with the Angle BOC, which is 115 degrees.
So, Arc BC will also be 115 degrees since its a central angle.
* An angle in a circle with the vertex at the circle's center*

Angle AOD would also be 115 degrees because its an opposite angle from Angle BOC.
So, Arc AD will also be 115 degrees because its a central angle.

Angle AOB will be 65 degrees because its supplementary to angle BOC.
*Two Angles that add up to 180 degrees*
So, Arc AB will be 65 degrees because its a central angle.

Angle DOC will also be 65 degrees because its an opposite angle to Angle AOB.
So, Arc DC will be 65 degrees because its a central angle.







For this Question we had to figure out how far from the centre of the circle is to the chord DC.
















It gives us:
Chord AB is 14 cm
Chord DC is 7 cm

AB runs through the centre of the circle, which makes it the diameter.
So the Radius is 7 cm.

Line EO bisects chord DC. Which makes it a right angle and cuts chord DC in half and makes each half will be 3.5 cm.

Then, make a radius OC and you then have a right triangle.

So far you will have:
Chord AB is 14 cm
Chord DC is 7 cm
Radius = 7 cm

OE = 3.5 cm


The next step is to use the Pythagorean theorem to find the length of line OE.

The answer will be 6.06 cm.








For this Question it is very similar to question two, where we have to find the length of from the centre of the circle to the chord. This time, we don't have a picture. So, we have to draw it.














They gave us:
Chord DC is 8 cm
Chord AB (diameter) is 10 cm
Radius is 5 cm

Line OE bisects chord DC, which makes it into a right triangle.

So we use the Pythagorean theorem.

Which gives us the answer 3.









Finally! For the last question! It is the same as the previous question, just switched around. We have to find out the diameter of a circle. Plus we have to draw the picture also.















They give us:
Chord AB is 16 cm
Line OE is 15cm (bisects chord AB, which makes a right triangle)
Half of Chord AB is 8

To find the answer you use the Pythagorean theorem.

Using that you will find the radius being 17 cm. Times that by two and you get the diameter 34 cm.


*The main thing that you have to remember though is NOT to write in paragraph form when you state the statement.*


p.s i cant explain well... so hopefully its somewhat helpful


The next blogger is Dianne..