Question

prove that cos theta-2coscubetheta by 2sincubetheta-sin theta=sin theta​

Answer 1

Answer:

a)2(cos

2

45

∘

+tan

2

60

∘

)−6(sin

2

45

∘

−tan

2

30

∘

)

=2[(

2

1

)

2

+(

3

)

2

]−6[(

2

1

)

2

−(

3

1

)

2

]

=2[

2

1

+3]−6[

2

1

−

3

1

]

=2[

2

7

]−6[

6

3−2

]

=7−1=6

b)2(cos

4

60

∘

+sin

4

60

∘

)−(tan

2

60

∘

+cos

2

45

∘

)+3sec

2

30

∘

=2[(

2

1

)

4

+(

2

1

)

4

]−[(

3

)

2

+(

2

1

)

2

]+3×

3

4

=2[

16

1

+

16

1

]−[3+

2

1

]+4

=2×

16

2

+4−

2

7

=

4

1

+4−

2

7

=

4

1+16−14

=

4

3