# CAST diagram in C3 working out?

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#1
When solving trigonometric functions which can be solved using the cast diagram, is it fine if I just use the few rules, for example 180-x for cos, or if I physically draw out the sin/cos/tan graphs?

The CAST diagram bores me so much that I can’t be bothered to learn how to implement it, and therefore I find the other two methods easier to use. Will I be penalised for not using the cast diagram in my working out by the examiner or not? I believe it’s fine to use any method you wish however I just want to be sure, thanks!
0
3 years ago
#2
(Original post by prospectivemath)
When solving trigonometric functions which can be solved using the cast diagram, is it fine if I just use the few rules, for example 180-x for cos, or if I physically draw out the sin/cos/tan graphs?

The CAST diagram bores me so much that I can’t be bothered to learn how to implement it, and therefore I find the other two methods easier to use. Will I be penalised for not using the cast diagram in my working out by the examiner or not? I believe it’s fine to use any method you wish however I just want to be sure, thanks!
You wouldn't be penalised for not using CAST. I certainly wasn't.

The few rules you can remember if you don't like CAST are the following:

as well as

for
0
3 years ago
#3
it is much easier to see what is going on with a quick sketch of the relevant curve.
0
3 years ago
#4
(Original post by prospectivemath)
When solving trigonometric functions which can be solved using the cast diagram, is it fine if I just use the few rules, for example 180-x for cos, or if I physically draw out the sin/cos/tan graphs?

The CAST diagram bores me so much that I can’t be bothered to learn how to implement it, and therefore I find the other two methods easier to use. Will I be penalised for not using the cast diagram in my working out by the examiner or not? I believe it’s fine to use any method you wish however I just want to be sure, thanks!
CAST shows some key properties of sin/cos/tan all in one diagram - it is useful for different types of trig questions, not just solving equations.

Drawing graphs may be slower but would be fine in an exam - CAST shouldn’t be compulsory in exams or in lessons.
0
3 years ago
#5
(Original post by the bear)
it is much easier to see what is going on with a quick sketch of the relevant curve.
Someone who is used to CAST would say the same about CAST

Both methods are fine.
0
3 years ago
#6
You can use any method; general solutions, quick sketch of the trig graphs or CAST. Personally, I like using CAST as it contains all the info needed for trig questions in C2/C3 and it's way quicker to draw.
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