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# Sine cosine rule

1. Heya just needed abit of help and explantion on how i can work this out. i tried the forumlas but they didnt work.
2. For this question, you don't need to use the sine or cosine rules. Instead, since you have the area of the triangle, you can use the two lengths and area to rearrange the formula for the area of a non right angled to find the angle.

Hope this helped

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3. If 1/2absin(c) = 4, then 1/2 (4.3)(4.3)sin(x) = 4, rearrange for sin(x).
Once you have one value for x(probably from a calculator), look at the graph of y= sin(x) to see other values of x that give the same value of sin(x) (whilst still having x less than 180 degrees so it can make a triangle)
4. (Original post by z_o_e)
Heya just needed abit of help and explantion on how i can work this out. i tried the forumlas but they didnt work.
Use the area of a triangle =
5. Nice MyMaths lmao
6. mymaths has a history of shwoing the answers as wrong when they are actually right
7. (Original post by AnnemarieV)
mymaths has a history of shwoing the answers as wrong when they are actually right
I once put in 13 years 0 months as an answer to a mymaths question and it marked it wrong saying the answer is 12 years 12 months

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8. (Original post by BobBobson)
I once put in 13 years 0 months as an answer to a mymaths question and it marked it wrong saying the answer is 12 years 12 months

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Heya can you help me on this question please

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9. (Original post by JN17)
If 1/2absin(c) = 4, then 1/2 (4.3)(4.3)sin(x) = 4, rearrange for sin(x).
Once you have one value for x(probably from a calculator), look at the graph of y= sin(x) to see other values of x that give the same value of sin(x) (whilst still having x less than 180 degrees so it can make a triangle)
Thank you x

I need help on the above

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10. (Original post by z_o_e)
Heya can you help me on this question please

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What help do you need? You seemed to have solved it. All you need to do is put that fraction into the inverse of cos function on your calculator.
On most calculators it looks like cos to the power of -1.
11. (Original post by BobBobson)
What help do you need? You seemed to have solved it. All you need to do is put that fraction into the inverse of cos function on your calculator.
On most calculators it looks like cos to the power of -1.
It said error

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12. Also for this
I need to find ourt angle BAC
I don't understand what angle is that

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13. (Original post by z_o_e)
Thank you x

I need help on the above

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As the person above said, you've done it, just simplify the squares and fraction and do cos-1(that answer) for the angle A
14. (Original post by z_o_e)
It said error

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It works fine when I put it into my calculator. What type of error is it?
15. (Original post by BobBobson)
It works fine when I put it into my calculator. What type of error is it?
Got it! !!

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16. (Original post by BobBobson)
It works fine when I put it into my calculator. What type of error is it?
For this I need to find BAC angle what angle is that?

I dont understand questions like that the wording BAC do I find angle B AND A AND C

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17. Posted from TSR Mobile
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18. (Original post by z_o_e)
For this I need to find BAC angle what angle is that?

I dont understand questions like that the wording BAC do I find angle B AND A AND C

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When an angle is written as "BAC" for example, it means the angle between the line BA and AC, or what you wrote down as simply A. People write it like that to avoid ambiguity. It doesn't mean to find all three angles.
19. (Original post by BobBobson)
When an angle is written as "BAC" for example, it means the angle between the line BA and AC, or what you wrote down as simply A. People write it like that to avoid ambiguity. It doesn't mean to find all three angles.
Between BA and AC is A

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20. (Original post by z_o_e)
Between BA and AC is A

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yeah.

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