VCE Specialist 3/4 Question Thread!

[Sine]

Where can I buy the worked solutions for the textbook?

Your teacher should have them avaliable to you

Need help with Q1 and Q2b: http://m.imgur.com/1rRQsZg

For Q1) I got the answer correct but had to guess one step which I still don't understand. I made cos(3t) and sin(3t) the subject, since the equation for a circle is sint squared + cost squared = 1, how does squaring cos3t and sin3t allow me to still get the correct answer?

Q2b) The answer has x = 4 but didn't show their method. I subbed the points and solved for the gradient which is undefined. How would I show that the line is x=4 mathematically?

Thanks

sint squared + cost squared = 1 so t is any angle in this case it is 3t (which is still an angle) since cos and sin have the same angle each of them squared sums to 1
 for 2(b) your working is fine imo. Gradient undinfied + passes through (4,y) is sufficient

[peter761]

Hey, does anyone mind helping me out with question 2b and 3b. Greatly appreciated.

[peanut]

Hey, does anyone mind helping me out with question 2b and 3b. Greatly appreciated.

2b) Find the magnitude of vector b and multiply that by the unit vector of a.

[nyggfany]

Hey, does anyone mind helping me out with question 2b and 3b. Greatly appreciated.

[Quantum44]

Can someone help me with 6b and 6c? I managed to do them but the answers I got were different to the textbook answers so I must have screwed up my method somewhere.

[nyggfany]

Can someone help me with 6b and 6c? I managed to do them but the answers I got were different to the textbook answers so I must have screwed up my method somewhere.

[strawberry7898]

Help with 8b please, answer is 7.1m/s not sure how to get there, answer to part a) was 4m/s^2 which I got correct. Question is attached 

[keltingmeith]

Help with 8b please, answer is 7.1m/s not sure how to get there, answer to part a) was 4m/s^2 which I got correct. Question is attached 

What did you try? We might be able to show you where you went wrong instead of just giving an answer.

[wyzard]

Help with 8b please, answer is 7.1m/s not sure how to get there, answer to part a) was 4m/s^2 which I got correct. Question is attached 

For maximum speed, we are assuming the box is travelling at it's terminal constant velocity where the forward force pushing the box is equal to resistance and the air resistance.

The amount of air resistance is then 3N, which you can use to evaluate the speed

[Syndicate]

Help with 8b please, answer is 7.1m/s not sure how to get there, answer to part a) was 4m/s^2 which I got correct. Question is attached 

Got beaten... but here's the answer.

Answer

The object will be at its terminal velocity when Fnet = 0 N. Therefore 4.5 = 1.5 + kv^2.

EDIT:: Like Euler said, it would be better if you post your working out first, and then understand where you went wrong (which is the reason why I put my working out in spoilers)

[Mattjbr2]

Hey guys
Can someone please tell me which step is incorrect? To me, it seems pretty straightforward and basic. But I keep getting the incorrect answer at the end I know that an easier method is possible - i.e.: line 1: sin²x*cos²x=(sinx*cosx)² and so on - but in my specific method, where is my error? Sorry for no Latex! it's really difficult for me to write out equations that way   

http://i.imgur.com/6Ek57fW.jpg

[nyggfany]

Hey guys
Can someone please tell me which step is incorrect? To me, it seems pretty straightforward and basic. But I keep getting the incorrect answer at the end I know that an easier method is possible - i.e.: line 1: sin²x*cos²x=(sinx*cosx)² and so on - but in my specific method, where is my error? Sorry for no Latex! it's really difficult for me to write out equations that way   

http://i.imgur.com/6Ek57fW.jpg

Step 4 to 5, you've forgotten the 1/2 in front of cos2x

[Mattjbr2]

Step 4 to 5, you've forgotten the 1/2 in front of cos2x

thanks lol

[manishmao]

Any help with this question.

The triangular base ABC of a tetrahedron has side lengths AB=15, BC=12 and AC=9. The apex D is 9 cm vertically above C.

Find the angles that the sloping edges make with the horizontal.

[Mattjbr2]

Any help with this question.

The triangular base ABC of a tetrahedron has side lengths AB=15, BC=12 and AC=9. The apex D is 9 cm vertically above C.

Find the angles that the sloping edges make with the horizontal.

If I understood the question correctly..