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C2 Radians

Doing A Level Maths : C2 :Radian Measures
Would appreciate it if you could help

The diagram shows the cross section ABCD of a glass prism. AD=BC=4cm and both are at right angles to DC. AB is the arc of circle, centre O and radius 6cm. given that angle AOB = 2theta and that the perimeter of the cross section is 2(7 + pi) cm.
a) show that (2theta + 2 sintheta - 1) = pi/3
b) verify that ?= pi/6

c) find the area of the cross section
Reply 1
Avatar for vc94
vc94
12
This is Ex.6D, Qn 13 from the Edexcel C2 textbook!

12*theta + 4+4+DC = 2( 7 + pi) ...the perimeter of ABCD.

But DC=AB.
Note that the midpoint of AB forms a right-angled triangle with O and A ...so you can make an equation for sin(theta).
Reply 2
Avatar for leonb2273
leonb2273
OP
Original post by vc94
This is Ex.6D, Qn 13 from the Edexcel C2 textbook!

12*theta + 4+4+DC = 2( 7 + pi) ...the perimeter of ABCD.

But DC=AB.
Note that the midpoint of AB forms a right-angled triangle with O and A ...so you can make an equation for sin(theta).


Thanks!
Reply 3
Avatar for Anhedonia
Anhedonia
Hi, I'm having problems with this question as well.

How exactly do you solve part b: Verify that theta = pi/6?
Reply 4
Avatar for Imposition
Imposition
Original post by leonb2273
Doing A Level Maths : C2 :Radian Measures
Would appreciate it if you could help

The diagram shows the cross section ABCD of a glass prism. AD=BC=4cm and both are at right angles to DC. AB is the arc of circle, centre O and radius 6cm. given that angle AOB = 2theta and that the perimeter of the cross section is 2(7 + pi) cm.
a) show that (2theta + 2 sintheta - 1) = pi/3
b) verify that ?= pi/6

c) find the area of the cross section


Has your teacher already started teaching you about radians??
Reply 5
Avatar for Anhedonia
Anhedonia
He just dumped a huge stack of questions on us. 'Teaching' in a broad sense I guess.
Reply 6
Avatar for Imposition
Imposition
Original post by Anhedonia
He just dumped a huge stack of questions on us. 'Teaching' in a broad sense I guess.


haha yeah I understand.
Reply 7
Avatar for leonb2273
leonb2273
OP
Original post by VictorDeLost
Has your teacher already started teaching you about radians??


I started A-Level Maths back in December 2010 in Year 10, and I have self taught myself C1-4, FP1, S1 M1 .The only bad things about doing it early is a) I now spend my lessons sitting at the back of a Year 11 (my year) maths lesson with a M2 textbook and people treat me like I don't exist and b) I am hated by some people: in Year 11 because I did the GCSE before them, in Year 12 because I did my GCSE with them, and in Year 13 because I did some A-Level modules with them.




Sorry if I went into too much detail!
Reply 8
Avatar for raheem94
raheem94
13
Original post by Anhedonia
Hi, I'm having problems with this question as well.

How exactly do you solve part b: Verify that theta = pi/6?


Try to understand the question of part 'b', this used the word 'verify' so you just have to check it. Here's how to do it:
[br]2θ+2sinθ−1=π3[br]θ=π6[br]2×π6+2sinπ6−1=π3+2×12−1=π3+1−1=π3[br]Verified[br][br]2\theta + 2sin\theta - 1 = \frac{\pi}3[br]\theta = \frac{\pi}6[br]2\times\frac{\pi}6 +2sin\frac{\pi}6 - 1 = \frac{\pi}3 + 2\times\frac12 - 1 = \frac{\pi}3 + 1 - 1 = \frac{\pi}3[br]Verified[br]
Reply 9
Avatar for Imposition
Imposition
Original post by leonb2273
I started A-Level Maths back in December 2010 in Year 10, and I have self taught myself C1-4, FP1, S1 M1 .The only bad things about doing it early is a) I now spend my lessons sitting at the back of a Year 11 (my year) maths lesson with a M2 textbook and people treat me like I don't exist and b) I am hated by some people: in Year 11 because I did the GCSE before them, in Year 12 because I did my GCSE with them, and in Year 13 because I did some A-Level modules with them.

Sorry if I went into too much detail!


Haters can hate. You do your thang bro!

I remember there was one kid who was soooo ahead of everyone back in secondary school, he was doing a-levels back in year 10. No one was angry at him, infact most people were jealous. Everyone was like, 'HOW DID YOU DO IT?'.
Anyway, that guy was(is) just ahead of the game(life) and you are too.

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