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4 years ago

If sin 21 = cos (5x+9) what is the value of x

Mathematics

1 answer:

n200080 [17]4 years ago

4 0

sin x = cos 54 = sin (90-54) = sin 46

Hence x = 46 deg

Same technique. Sin 21 = cos (5x+9) = sin (90-5x-9)

81-5x = 21

Or 5x = 60

Or x = 12 deg

hope it helps

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General Formulas and Concepts:

Pre-Calculus

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Step-by-step explanation:

Step 1: Define

Identify

$\displaystyle \int\limits^0_\infty {cos(x)} \, dx$

Step 2: Integrate

[Improper Integral] Rewrite: $\displaystyle \lim_{a \to \infty} \int\limits^0_a {cos(x)} \, dx$
[Integral] Trig Integration: $\displaystyle \lim_{a \to \infty} sin(x) \bigg| \limits^0_a$
[Integral] Evaluate [Integration Rule - FTC 1]: $\displaystyle \lim_{a \to \infty} sin(0) - sin(a)$
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Since we are dealing with infinity of functions, we can do a numerous amount of things:

Since -sin(x) is a shift from the parent graph sin(x), we can say that -sin(∞) = sin(∞) since sin(x) is an oscillating graph. The values of -sin(x) already have values in sin(x).
Since sin(x) is an oscillating graph, we can also say that the integral actually equates to undefined, since it will never reach 1 certain value.

∴ $\displaystyle \int\limits^0_\infty {cos(x)} \, dx = sin(\infty) \ or \ \text{unde}\text{fined}$

Topic: AP Calculus AB/BC (Calculus I/I + II)

Unit: Improper Integrals

Book: College Calculus 10e

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