Monthly Archives: May 2009

Chord Theorems

Starting off with some definitions and initial theorems. The chord theorems could just as easily be called the arc theroms as chords and arcs have the same endpoints.

Note: I fixed up the mistake with the perpendiculars when proving theorem 3, obviously the audio still mentions the mistake.

lesson notes: 01-definitions-chord-theorems

audio:  01 definitions & chord theorems

slidecast:

11X1 T07 01 definitions & chord theorems

That bird question

For those that don’t have Fitzpatick, the question was;

A stone is thrown so that it will hit a bird at the top of a pole. However, at the instant the stone is thrown, te bird flies away in a horizontal straight line at a speed of 10 m/s. The stone reaches a height double that of the pole and, in its descent, touches the bird. Find the horizontal component of the velocity of the stone.

Having thought about this with a fresh mind, it reminded me a bit of last year’s HSC question which was a projectile motion question where you didn’t need to use projectile motion, but rather used ideas about he quaratic function (i.e. parabola).

Hope you like the solution, I think it ended up being quite neat.

fitz-25d-q17

Moral of the story; if you are sitting on a pole and someone throws a rock at you, fly towards the thrower NOT away. Dumb bird!!!!

Similar Triangles

Congruent triangles are just a special case of similar triangles, so all of the congruent triangle tests work with similar triangles. The difference is that th ratio of sides in congruent triangles is 1:1, whereas similar triangles could be any ratio.

lesson notes: 05-similar-triangles

audio: 05 similar triangles

slidecast:

11X1 T06 05 Similar Triangles