Math

posted by .

Would someone verify these answers.

1. A person waves his hand back and forth, where their finger tips move past the starting position 4 cm in each direction. If he waves 20 times every 15s, what sine equation models the movement of the hand if the hand starts in the upright position and the right direction will be taken as positive?

a)y=4sin(20pi/15 x t)
b)y=4sin(30pi/20 x t)
c)y=4sin(40pi/15 x t)
c)y=8sin(30pi/20 x t)

Answer: A
--------------------------------------
2. Which of the six trig functions are positive in quad III?

Ans: Tangent and cotangent
---------------------------------------
3. What is the exact value of sin(3pi/2)?

Answer: 3pi/2=270 degree, equals to -1

Therefor exact value -1.

---------------------------------------

  • Math -

    1.
    If he waved once every second, the frequency would be 1. you'd have sin(2πt).
    If he waved n times, you'd have sin(2πnt).
    Would you like to change your answer to C?

    2. ok

    3. ok

  • Math - PS -

    Hmm. If a wave is defined as moving away from the starting point and back, your A answer is correct.

    If a wave is defined as a complete cycle away and back in each direction, then the answer would be C.

  • Math -

    I am confused for number 3

  • Math -

    sin(270) = sin(90+180) = sin90cos180 + cos90sin180 = 1(-1) + 0*0 = -1

    or, at 270 deg, y=-1, x=0, r=1

    sin = y/r = -1/1 = -1

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Susane

    Two identical traveling waves moving in the same direction are out of phase by pi/2 rad. What is the amplitude Y of the two combining waves. I have no clue how to do this. The answer according to the back of the book is 1.4y max. If …
  2. Physical Science

    Here are a few questions that I have answered; can someone please check if they are correct?
  3. physics

    An earthquake generates three kinds of waves: surface waves (L waves), which are the slowest and weakest; shear (S) waves, which are transverse waves and carry most of the energy; and pressure (P) waves, which are longitudinal waves …
  4. physics

    An earthquake generates three kinds of waves: surface waves (L waves), which are the slowest and weakest; shear (S) waves, which are transverse waves and carry most of the energy; and pressure (P) waves, which are longitudinal waves …
  5. physics

    An earthquake generates three kinds of waves: surface waves (L waves), which are the slowest and weakest; shear (S) waves, which are transverse waves and carry most of the energy; and pressure (P) waves, which are longitudinal waves …
  6. physics

    An earthquake generates three kinds of waves: surface waves (L waves), which are the slowest and weakest; shear (S) waves, which are transverse waves and carry most of the energy; and pressure (P) waves, which are longitudinal waves …
  7. PHYSICS - Waves

    Can someone tell me how to get the answer to this question?
  8. Math

    A swing has a maximum height of 2 m and a minimum height of 0.5 m and it takes 3 seconds to get from the maximum height to the minimum height. Approximate the instantaneous rate of change 1 second into the fall using the difference …
  9. physics

    Q1-In hugyen's principle of wave theory why the waves are move in forward direction not in backward direction means they move forward as a new source why not in backward direction?
  10. Science

    Im sorry i am totally stumped What is the main difference between mechanical and electromagnetic waves A. Mechanical waves involve the transfer of energy; electromagnetic waves do not B. Mechanical waves require a medium to travel …

More Similar Questions