- #1

mathuravasant

- 10

- 0

Find the first two positive x-intercepts for y= -2cos(3(x-25°)) +1

(Can someone help me for this)

(Can someone help me for this)

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- MHB
- Thread starter mathuravasant
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- #1

mathuravasant

- 10

- 0

Find the first two positive x-intercepts for y= -2cos(3(x-25°)) +1

(Can someone help me for this)

(Can someone help me for this)

- #2

- 1,844

- 811

Well, some basic algebra first:Find the first two positive x-intercepts for y= -2cos(3(x-25°)) +1

(Can someone help me for this)

\(\displaystyle 0 = -2 ~ cos(3 (x - 25) ) + 1\)

\(\displaystyle -1 = -2 ~ cos(3 (x - 25) )\)

\(\displaystyle \dfrac{1}{2} = cos(3 (x - 25) )\)

Where are the first two places you find cos(y) = 1/2?

Can you finish?

-Dan

- #3

mathuravasant

- 10

- 0

- #4

- 1,844

- 811

Start here: Where are the first two places you find cos(y) = 1/2? If you need to use your calculator! Graph it! Do something. I have no idea how you got your answer so I can't address what you might have done wrong. Please tell us how you are doing your calculations.

The first

-Dan

- #5

HOI

- 923

- 2

Since cos(3(x-25))= 1/2, 3(x- 25)= 3x- 75= 60 so 3x= 60+ 75= 135, x= 45 degrees.

Since cos(180- x)= COS(x), cos(180- 60)= cos(120)= 1/2 so we can also have 3x- 75= 120, 3x= 195, x= 65 degrees.

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