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Double Angle Identities

Was always absolutely rubbish at proving, even more so for A2 so need some help please! Question 4

WP_001679.jpg

The only thing I've got here is cotx = 1/tanx and then I don't know what to do
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Avatar for Zhy
Zhy
17
What happens when you add tan and cot?
Original post by RoseBrilliante
Was always absolutely rubbish at proving, even more so for A2 so need some help please! Question 4

WP_001679.jpg

The only thing I've got here is cotx = 1/tanx and then I don't know what to do


write tan and cot in terms of sin and cos, then add the two fractions.
Reply 3
Avatar for gdunne42
gdunne42
21
Original post by RoseBrilliante
Was always absolutely rubbish at proving, even more so for A2 so need some help please! Question 4

WP_001679.jpg

The only thing I've got here is cotx = 1/tanx and then I don't know what to do


You have no tan or cot in the RHS + you know it's double angles and so must at some point get a 2sinxcosx to turn into a sin2x
SO need to rewrite in terms of sin and cos and add them up.....
You know from C2 that tanx = sinx/cosx and hence I'm sure can come up with something for cotx=


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