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Tatiana [17]
3 years ago
7

Provethat2 cos (A +45°) cos (B-45°) = cos 2A​

Mathematics
1 answer:
wolverine [178]3 years ago
6 0

Answer:

Step-by-step explanation:

2 cos(A+45)cos (B-45)

=2[cos A cos 45-sin A sin 45][cos B cos 45+sin B sin 45]

=2[cos A ×1/√2-sin A ×1/√2][cos B×1/√2+sin B×1/√2]

=2[1/√2(cos A-sin A)][1/√2(cos B-sin B]

=2×1/√2×1/√2 (cos A-sin A)(cos B+sin B)

=cosA cos B+cos A sin B-sin A cos B-sin A sin B

=cos A cos B-sin A sin B-(sin A cos B-cos A sin B)

=cos (A+B)-sin (A-B)

i think there should be A in place of B.

then

=cos (A+A)-sin (A-A)

=cos 2A-sin 0

=cos 2A

as sin 0=0

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strojnjashka [21]

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Step-by-step explanation:

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2 years ago
A 40-foot ladder is leaning against a building and forms a 29.32° angle with the ground. how far away from the building is the b
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The distance between the building and the ladder is 34.876 foot.

<h3>What is a Right Triangle?</h3>

A triangle in which one of the angle measure is equal to 90 degree is called a right triangle.

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cos 29.32 = Base /  Hypotenuse

cos 29.32 = Base / 40

0.8718 × 40 = Base

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Base of the ladder = 34.876 foot

To learn more about trigonometric functions from the given link

brainly.com/question/24336684

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