Question

find value of cos22½​

Answer 1

Answer:

11

Step-by-step explanation:

you can also try 22/2

hope it helps ☺

please mark brainliest answer....

Answer 2

Answer:

22½° lies in the first quadrant.

Therefore, sin 22½° is positive.

For all values of the angle A we know that, cos A = 2 cos2

A

2

- 1

⇒ 1 + cos A = 2 cos2

A

2

⇒ 2 cos2

A

2

= 1 + cos A

⇒ 2 cos2 22½˚ = 1 + cos 45°

⇒ cos2 22½˚ =

1+cos45°

2

⇒ sin2 22½˚ =

1+

1

√

2

2

, [Since we know cos 45° =

1

√2

]

⇒ cos 22½˚ =

√

1

2

(1+

1

√

2

)

, [Since, cos 22½˚ > 0]

⇒ cos 22½˚ =

√

√

2

+1

2

√

2

⇒ cos 22½˚ =

1

2

√

2+

√

2

Therefore, cos 22½˚ =

1

2

√

2+

√

2

ⁿᵒʷ ᶠᵘᶜᵏ ᵗʰⁱˢ... XD