# Trigonometry

Suppose you were at the beach and notice that at 1:00 pm the tide is in, that is, the depth of water is at its deepest. At that time you find that the depth of the water at the end of the pier is 1.9 meters. At 7:00 that evening when the tide is out, the depth of the water is 1.1 meters. Assuming that the depth of the water varies sinusoidally with time, find an equation that will model the depth of the water.

A. y=1.5cos(pi/3(x-7)) + 0.4

B. y=1.5cos(pi/6(x-7)) + 0.4

C. y=0.4cos(pi/6(x-7)) + 1.5

D. y=-0.4cos(pi/6(x-7)) + 1.5

1. 👍 0
2. 👎 0
3. 👁 154
1. half-period is 6 hours, so a full period is 12 hours. So, if 2pi/k = 12, k = pi/6.

The max-min=1.9-1.1 = 0.8, so the amplitude is 0.4

So, the choice is C or D.

The midpoint is (1.9+1.1)/2 = 1.5, so we're still looking at C or D.

Since we apparently want a cosine function, whose minimum is at x=7, that would make it (D) since (C) has its max at x=7.

1. 👍 0
2. 👎 0
posted by Steve

## Similar Questions

1. ### language

is my free verse peom correct? can you check for any errors? thank you. Sitting On The Beach Sitting on the beach Watching the sun set, It makes me calm. Sitting on the beach Watching people walking past, Holding hands. Sitting on

asked by john on April 17, 2009
2. ### Math/Algebra

On Dolphin Beach, the high tide is 2.2 meters and only occurs at 12 a.m. and 12 p.m. The low tide is 1 meter and only occurs at 6 a.m. and 6 p.m. Which function models the height of the tide t hours after 12 a.m.? a.

asked by Jessica on April 8, 2018
3. ### language

This is my whole free verse poem. i hope it fully sends this time. could you please take a look at it sitting on the beach Sitting on the beach watching the sun set, It make me calm. Sitting on the beach watching people walking

asked by john on April 17, 2009
4. ### Science

1.When the effects of the moon and sun work together, this is what kind of tide? A)Neap tide B)Fall tide C)Spring tide** D)New moon tide

asked by katrina on December 1, 2016
5. ### science

you observe a high tide at 3:00 a.m. If it takes about 6 1/4 hours for the tide to change from hight to low, whic of the following statements is correct? A. The next low tide will be at 9:15am B. The afternoon low tide will be at

asked by kayci on May 12, 2010
6. ### Math

Two ocean beaches are being affected by erosion. The table shows the width, in feet, of each beach at high tide measured where 1995 is represented by year 0. Western beach width Dunes beach Year number (in feet) width (in feet) 0

asked by Hannah on December 10, 2015
7. ### math

Can't figure this one out. The oceans' tide levels vary based on the phases of the moon. Find the percent decrease in tide levels when high tide is 4.25 ft and low tide is 0.75 ft above sea level.

asked by emma on October 21, 2014
8. ### Complete subjects and predicates

Underline the complete subject with one line and circle the simple subject. Underline the complete predicate with two lines and circl the simple predicate. 1. A young girl walks carefully along the rocky shore. 2. Carmen notices

asked by Diane on March 14, 2011
9. ### Trigonometry

At the ocean, it is known that the tide follows a trigonometric path. At high tide, the water comes in to a point 1 meter from where I placed a flag. At low tide, the water comes in to a point 11 meters from the same flag. The

asked by Fred on August 15, 2010
10. ### Language arts poetry

in the poem the tide rises the tide falls Longfellow uses figurative language in repetition in a paragraph identify the symbolism and repetition used in the poem explain how both are connected to the meaning of the poem include

asked by sarah on May 16, 2017

More Similar Questions