Question 4 (a) (ii) (1 Viewer)

[Michaelmoo]

Hey. For question four of the 2008 HSC paper, it said the circle touched all three sides of the triangle. Does that mean you can assume the sides of teh Triangle KLM are all Tangents to the circle.

Need that for the second proof...

What is another way to do it??

 

[lordo]

yeah i couldnt find any other way to do it so i assumed they were tangents =) i couldnt do part i) without assuming that

 

[revanchist]

Short answer: yes.
Long answer: you can assume they are tangents, because you need a perpendicular line form where the circle touches the sides to it's center to make working out the area easy. If it was not perpendicular I'm sure you couldn't have gotten the result asked. Tangents didn't actually cross my mind at all, the fact that it was perpendicular was just assumed.
Once that was assumed and you got part i) done, you assume the same thing for part ii). Simple

 

[Michaelmoo]

Short answer: yes.
Long answer: you can assume they are tangents, because you need a perpendicular line form where the circle touches the sides to it's center to make working out the area easy. If it was not perpendicular I'm sure you couldn't have gotten the result asked. Tangents didn't actually cross my mind at all, the fact that it was perpendicular was just assumed.
Once that was assumed and you got part i) done, you assume the same thing for part ii). Simple

Yep thats how I thought you can attack the question. Assume they're tangents, draw a perpendicular line to each tangent, sum of all areas, factorise and you got your proof...

Thanks.

 

[Michaelmoo]

use your brains people. you have a couple of bloody planks resting on balls. the planks don't hover in midair, or penetrate the balls?

Its does not mention planks and wheel* till part (iii), next time you use yours