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C3 maximum of graph question

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
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:
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
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)
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?
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!
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.
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!
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)
Original post by BananaBanana101
Question:


Can you explain part (a) of the question please

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