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3 years ago

Given the diagram below, what is cos(45*)? A. B. C. D.

Mathematics

1 answer:

alina1380 [7]3 years ago

3 0

Answer:

The answer is option B

Step-by-step explanation:

To find cos 45° we must first find the adjacent and the hypotenuse

Let the adjacent be x

Let the hypotenuse be h

To find the adjacent we use tan

tan ∅ = opposite / adjacent

From the question

the opposite is 9

So we have

tan 45 = 9 / x

x tan 45 = 9

but tan 45 = 1

x = 9

Since we have the adjacent we use Pythagoras theorem to find the hypotenuse

That's

h² = 9² + 9²

h² = 81 + 81

h² = 162

h = √162

h = 9√2

Now use the formula for cosine

cos∅ = adjacent / hypotenuse

The adjacent is 9

The hypotenuse is 9√2

So we have

cos 45 = 9/9√2

We have the final answer as

Hope this helps you

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3 years ago

The circumference of the ellipse approximate. Which equation is the result of solving the formula of the circumference for b?

Serhud [2]

Answer:

$b = \sqrt{\frac{C^{2} }{2(\pi )^{2} } - a^{2}}$

Step-by-step explanation:

Given - The circumference of the ellipse approximated by $C = 2\pi \sqrt{\frac{a^{2} + b^{2} }{2} }$ where 2a and 2b are the lengths of 2 the axes of the ellipse.

To find - Which equation is the result of solving the formula of the circumference for b ?

Solution -

$C = 2\pi \sqrt{\frac{a^{2} + b^{2} }{2} }\\\frac{C}{2\pi } = \sqrt{\frac{a^{2} + b^{2} }{2} }$

Squaring Both sides, we get

$[\frac{C}{2\pi }]^{2} = [\sqrt{\frac{a^{2} + b^{2} }{2} }]^{2} \\\frac{C^{2} }{(2\pi)^{2} } = {\frac{a^{2} + b^{2} }{2} }\\2\frac{C^{2} }{4(\pi)^{2} } = {{a^{2} + b^{2} }$