scribin' at the last minute...

* sorry guys i did this at the last possible time i was suppose to work until 10:00pm ended up working until 11:00pm.

- Well, today we did a quiz on our circle geometry. Here are the questions on the quiz so you can try it again or for the first time if you were not there. In the end I'll post up the answers.
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Circle Geometry Quiz 2

(1) angle BOC = 115'. Find the measures of arcs AB, BC, CD, and AD. Justify your solution (4 marks)

(2) If the measure of chord AB is 14cm and the measure and the measure of chord DC is 7 cm, how far from the centre of the circle is chord DC? Justify your solution. (4 marks)


(3) How far is a chord of length 8 cm from the centre of a circle with a diameter of 10cm? (2 marks)

(4) What is the diameter of a circle in which a chord 16 cm long is 15 cm from the centre? (3 marks)

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ANSWERS:* i wish i could've made it into columns

(2) STATEMENT / REASON
AB = 14 cm / GIVEN
DC = 7 cm / GIVEN
OB = 7 cm & AO = 7 cm / RADII, AND AB DIAMETER
DE = 3.5 cm & EC = 3.5 cm / PERPENDICULAR BISECTOR THEOREM
OC = 7 cm / Radius
OE = 6.06 cm / PYTHAGOREAN THEOREM

a^2 + b^2 = c^2
3.5^2 + b^2 = 7^2
12.25 + b^2 = 49
49 - 12.25 = b^2
b^2 = 36.75
b = 6.06

(3) PYTHAGOREAN THEOREM
a^2 + b^2 = c^2
4^2 + b^2 = 5^2
16 + b^2 = 25
25 - 16 = b^2
b^2 = 9
b = 3

The chord is 3 cm away from the centre of the circle.

(4) PYTHAGOREAN THEOREM
a^2 + b^2 = c^2
15^2 + 8^2 = c^2
c^2 = 289
c = 17
diameter = 17 x 2 = 34 cm

The diameter of the circle is 34 cm.

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* PHEW.... sorry again guys well next scribe will be....

rannell d.

hah =) have fun rannell.