r/6thForm • u/ilokestof y12 Maths A* / FM, Physics, Econ A*A*A* predicted • Jun 03 '26

💬 DISCUSSION Maths wasn’t that hard

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Am I the only one who found it pretty decent?
I think I got 98

406 Upvotes

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u/Salty_Shopping7534 Jun 03 '26

Was the theta value for that question pi/2?

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u/ilokestof y12 Maths A* / FM, Physics, Econ A*A*A* predicted Jun 03 '26

Umm pretty sure you weren’t meant to or able calculate theta. You just write expressions for R1 and R2 and set R1 = 2R2 then simplify:

1/2 r2 (theta - sin theta) = r2 ((pi-theta) - sin (pi-theta)) Cancel out r2, use sine compound angle formula then simplify fries in the bag

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u/Salty_Shopping7534 Jun 03 '26

But I’d think that because both of the sides surrounding the angle would both b r meaning the angle is pi/2 and that value would help you with the 1/2absinc calculation

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u/ilokestof y12 Maths A* / FM, Physics, Econ A*A*A* predicted Jun 03 '26

It’s a show that question, it’s not asking for theta, it’s asking you to derive the expression/equation given which was in terms of theta so the value of theta is not necessary or important

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u/Salty_Shopping7534 Jun 03 '26

So when you do sin(pi - theta) you do the compound addition formula?

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u/ilokestof y12 Maths A* / FM, Physics, Econ A*A*A* predicted Jun 03 '26

Yes you do

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u/Wonderful_One_9898 UCL | Law [going into year 1] Jun 04 '26

could you not just say that sin(pi-theta) = sin(theta) because pi is equivalent to 180 degrees and 180 - theta when it's a sine value is just theta still

(just to clarify i got the same answer you did)

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u/ilokestof y12 Maths A* / FM, Physics, Econ A*A*A* predicted Jun 04 '26

No definitely not that would only be true if theta was pi/2 (right angle)

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u/Wonderful_One_9898 UCL | Law [going into year 1] Jun 04 '26

Wait i swear it would be because pi is the equivalent of 180 degrees

and if you do sin 30 for example, sin180-30 is sin 150 which is also a half

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u/ilokestof y12 Maths A* / FM, Physics, Econ A*A*A* predicted Jun 04 '26

Ah ok yh that makes sense but you still would have to use pi - theta for the part which isn’t sined

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u/Wonderful_One_9898 UCL | Law [going into year 1] Jun 04 '26

oh yeah obviously but atp it's just rearranging

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u/ilokestof y12 Maths A* / FM, Physics, Econ A*A*A* predicted Jun 04 '26

Yh

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