3.
The t results
Let t tan
2
2 tan
tan 2
1 tan 2
2
2t
tan
1 t 2
4.
The t results
Let t tan
2
2t
2 tan
tan 2
1 t 2
1 tan 2
2
2t
tan
1 t 2
5.
The t results
Let t tan
2 1 t2
2t
2 tan
tan 2
1 t 2
1 tan 2
2 h 2t 1 t
2 2
2 2
2t
tan
1 t 2 4t 2 1 2t 2 t 4
t 4 2t 2 1
t 1
2 2
6.
The t results
Let t tan
2 1 t2
2t
2 tan
tan 2
1 t 2
1 tan 2
2 h 2t 1 t
2 2
2 2
2t
tan
1 t 2 4t 2 1 2t 2 t 4
t 4 2t 2 1
t 1
2
If t tan ;
2
2
2t
tan
1 t 2
7.
The t results
Let t tan
2 1 t2
2t
2 tan
tan 2
1 t 2
1 tan 2
2 h 2t 1 t
2 2
2 2
2t
tan
1 t 2 4t 2 1 2t 2 t 4
t 4 2t 2 1
t 1
2
If t tan ;
2
2
2t 2t
tan sin
1 t 2 1 t 2
8.
The t results
Let t tan
2 1 t2
2t
2 tan
tan 2
1 t 2
1 tan 2
2 h 2t 1 t
2 2
2 2
2t
tan
1 t 2 4t 2 1 2t 2 t 4
t 4 2t 2 1
t 1
2
If t tan ;
2
2
2t 2t 1 t2
tan sin cos
1 t 2 1 t 2 1 t2
9.
The t results
Let t tan
2 1 t2
2t
2 tan
tan 2
1 t 2
1 tan 2
2 h 2t 1 t
2 2
2 2
2t
tan
1 t 2 4t 2 1 2t 2 t 4
t 4 2t 2 1
t 1
2
If t tan ;
2
2
2t 2t 1 t2
tan sin cos
1 t 2 1 t 2 1 t2
Note:
2t
If t tan ; tan 2
1 t2
10.
The t results
Let t tan
2 1 t2
2t
2 tan
tan 2
1 t 2
1 tan 2
2 h 2t 1 t
2 2
2 2
2t
tan
1 t 2 4t 2 1 2t 2 t 4
t 4 2t 2 1
t 1
2
If t tan ;
2
2
2t 2t 1 t2
tan sin cos
1 t 2 1 t 2 1 t2
Note:
2t 2t
If t tan ; tan 2 If t tan 2 ; tan 4
1 t2 1 t2
11. 1 cos x x
e.g. i Show that t , where t tan
sin x 2
12. 1 cos x x
e.g. i Show that t , where t tan
sin x 2
1 t2
1 cos x 1 1 t 2 x
x is double ,
2
sin x 2t
1 t2 so t results can be used for sin x,cos x
13. 1 cos x x
e.g. i Show that t , where t tan
sin x 2
1 t2
1 x
1 cos x 1 t 2
x is double ,
2
sin x 2t
1 t2 so t results can be used for sin x,cos x
1 t 2 1 t 2
2t
14. 1 cos x x
e.g. i Show that t , where t tan
sin x 2
1 t2
1 x
1 cos x 1 t 2
x is double ,
2
sin x 2t
1 t2 so t results can be used for sin x,cos x
1 t 2 1 t 2
2t
2t 2
2t
t
15. 2 tan 75
ii Use t tan to simplify
2 1 tan 2 75
16. 2 tan 75
ii Use t tan to simplify
2 1 tan 2 75
Let t tan 75 ;
17. 2 tan 75
ii Use t tan to simplify
2 1 tan 2 75
Let t tan 75 ;
i.e. 75
2
150
18. 2 tan 75 2 tan 75 2t
ii Use t tan to simplify
2 1 tan 2 75 1 tan 2 75 1 t 2
Let t tan 75 ;
i.e. 75
2
150
19. 2 tan 75 2 tan 75 2t
ii Use t tan to simplify
2 1 tan 2 75 1 tan 2 75 1 t 2
Let t tan 75 ; sin
i.e. 75
2
150
20. 2 tan 75 2 tan 75 2t
ii Use t tan to simplify
2 1 tan 2 75 1 tan 2 75 1 t 2
Let t tan 75 ; sin
sin150
i.e. 75 1
2
150 2
21. 2 tan 75 2 tan 75 2t
ii Use t tan to simplify
2 1 tan 2 75 1 tan 2 75 1 t 2
Let t tan 75 ; sin
sin150
i.e. 75 1
2
150 2
1 sin cos
iii Prove tan
1 sin cos 2
22. 2 tan 75 2 tan 75 2t
ii Use t tan to simplify
2 1 tan 2 75 1 tan 2 75 1 t 2
Let t tan 75 ; sin
sin150
i.e. 75 1
2
150 2
1 sin cos
iii Prove tan
1 sin cos 2 2t 1 t 2
1 sin cos 1 1 t 2 1 t 2
Let t tan ;
2 1 sin cos 2t 1 t 2
1
1 t 2
1 t2
23. 2 tan 75 2 tan 75 2t
ii Use t tan to simplify
2 1 tan 2 75 1 tan 2 75 1 t 2
Let t tan 75 ; sin
sin150
i.e. 75 1
2
150 2
1 sin cos
iii Prove tan
1 sin cos 2 2t 1 t 2
1 sin cos 1 1 t 2 1 t 2
Let t tan ;
2 1 sin cos 2t 1 t 2
1
1 t 1 t2
2
1 t 2 2t 1 t 2
1 t 2 2t 1 t 2
24. 2 tan 75 2 tan 75 2t
ii Use t tan to simplify
2 1 tan 2 75 1 tan 2 75 1 t 2
Let t tan 75 ; sin
sin150
i.e. 75 1
2
150 2
1 sin cos
iii Prove tan
1 sin cos 2 2t 1 t 2
1 sin cos 1 1 t 2 1 t 2
Let t tan ;
2 1 sin cos 2t 1 t 2
1
1 t 1 t2
2
1 t 2 2t 1 t 2
1 t 2 2t 1 t 2
2t 2 2t
2 2t
25. 2 tan 75 2 tan 75 2t
ii Use t tan to simplify
2 1 tan 2 75 1 tan 2 75 1 t 2
Let t tan 75 ; sin
sin150
i.e. 75 1
2
150 2
1 sin cos
iii Prove tan
1 sin cos 2 2t 1 t 2
1 sin cos 1 1 t 2 1 t 2
Let t tan ;
2 1 sin cos 2t 1 t 2
1
1 t 1 t2
2
1 t 2 2t 1 t 2
1 t 2 2t 1 t 2
2t 2 2t
2 2t
2t t 1
2 1 t
26. 2 tan 75 2 tan 75 2t
ii Use t tan to simplify
2 1 tan 2 75 1 tan 2 75 1 t 2
Let t tan 75 ; sin
sin150
i.e. 75 1
2
150 2
1 sin cos
iii Prove tan
1 sin cos 2 2t 1 t 2
1 sin cos 1 1 t 2 1 t 2
Let t tan ;
2 1 sin cos 2t 1 t 2
1
1 t 1 t2
2
1 t 2 2t 1 t 2
1 t 2 2t 1 t 2
2t 2 2t
2 2t
2t t 1
t tan
2 1 t 2
27.
(iv) By making the substitution t tan or otherwise,
2
show that cosec cot cot 2005 Extension 1 HSC Q4b)
2
28.
(iv) By making the substitution t tan or otherwise,
2
show that cosec cot cot 2005 Extension 1 HSC Q4b)
2
1 t2 1 t2
cosec cot
2t 2t
29.
(iv) By making the substitution t tan or otherwise,
2
show that cosec cot cot 2005 Extension 1 HSC Q4b)
2
1 t2 1 t2
cosec cot
2t 2t
2
2t
1
t
30.
(iv) By making the substitution t tan or otherwise,
2
show that cosec cot cot 2005 Extension 1 HSC Q4b)
2
1 t2 1 t2
cosec cot
2t 2t
2
2t
1
t
cot
2
31.
(iv) By making the substitution t tan or otherwise,
2
show that cosec cot cot 2005 Extension 1 HSC Q4b)
2
1 t2 1 t2
cosec cot
2t 2t
2
2t
1
t
cot
2
Exercise 2B; 1def, 3ace, 4bcf, 5aceg, 6, 8bd, 10a