# C3 maximum of graph question

#1
Can someone please explain to me why the answer to (b) (I) is 4/12-10
I feel like I don't fully understand how to calculate the maximum and minimum of a graph

Thank you
0
#2
(Original post by BananaBanana101)
Can someone please explain to me why the answer to (b) (I) is 4/12-10
I feel like I don't fully understand how to calculate the maximum and minimum of a graph

Thank you

Question:
0
6 years ago
#3
(Original post by BananaBanana101)
Can someone please explain to me why the answer to (b) (I) is 4/12-10
I feel like I don't fully understand how to calculate the maximum and minimum of a graph

Thank you
Pretty sure you have to use your answer to part a, what did you get for that part?

Posted from TSR Mobile
1
#4
(Original post by Ben4)
Pretty sure you have to use your answer to part a, what did you get for that part?

Posted from TSR Mobile

10cos(theta - 0.927)

(Correct)
0
6 years ago
#5
(Original post by BananaBanana101)
10cos(theta - 0.927)
So you can write:
P(theta) = 4/(12-10cos(theta-0.927))

Since this is always positive, you know that P is a maximum when the denominator ( 12 - 10cos(theta-0.927) ) on the right is as small as possible.

Can you think what the smallest value of 12 - 10cos(theta-0.927) is and when it occurs?
0
#6
(Original post by studentro)
So you can write:
P(theta) = 4/(12-10cos(theta-0.927))

Since this is always positive, you know that P is a maximum when the denominator ( 12 - 10cos(theta-0.927) ) on the right is as small as possible.

Can you think what the smallest value of 12 - 10cos(theta-0.927) is and when it occurs?
So inverse cos -1 = pie add 0.927

Out of curiosity why am I allowed to do -10cos(theta - 0.927)

Thank you!
0
6 years ago
#7
(Original post by BananaBanana101)
So inverse cos -1 = pie add 0.927

Out of curiosity why am I allowed to do -10cos(theta - 0.927)

Thank you!
Sorry, I misread. The denominator is 12+10cos(theta-0.927).
Find the minimum value this takes and the value of theta at which it occurs.
0
#8
(Original post by studentro)
Sorry, I misread. The denominator is 12+10cos(theta-0.927).
Find the minimum value this takes and the value of theta at which it occurs.
No what you said is correct to the mark scheme!
0
6 years ago
#9
(Original post by BananaBanana101)
No what you said is correct to the mark scheme!
What I said would get you the correct minimum value of P but an incorrect value of theta (unless you made a mistake that cancelled out mine! xD)
0
6 years ago
#10
(Original post by BananaBanana101)
Question:
Can you explain part (a) of the question please
0
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