Question

(cos²33°- cos²57°)/(sin 21°- cos 21°)​

Answer 1

Answer:

Using trignometric rule:

cosθ=sin(90−θ)

By using this, we get

sin21−cos21

cos

2

33−cos

2

57

=

sin21−sin(90−21)

cos

2

33−sin

2

(90−57)

=

sin21−sin69

cos

2

33−sin

2

33

Now by using trignometric rule,

cos

2

A−sin

2

A=cos2A and sinA−sinB=2cos(

2

A+B

)sin(

2

A−B

)

Thus

sin21−sin69

cos

2

33−sin

2

33

=

2cos45sin24

cos66

=

2

2

1

sin24

sin(90−66)

=

2

sin24

sin24

=

2

1

Step-by-step explanation:

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