# marie darling

Most popular questions and responses by marie darling
1. ## precalculus

Outside temperature over a day can be modelled as a sinusoidal function. Suppose you know the temperature is 80 degrees at midnight and the high and low temperature during the day are 90 and 70 degrees, respectively. Assuming t is the number of hours since

2. ## precalculus

The four sequential sides of a quadrilateral have lengths a=3.6, b=5.3, c=8.4, and d=10.2 (all measured in yards). The angle between the two smallest sides is alpha = 117°. What is the area of this figure?

3. ## trigonometry

A truck with 48-in.-diameter wheels is traveling at 55 mi/h. Find the angular speed of the wheels in rad/min, *hint convert miles to inches & hours to minutes: __rad/min How many revolutions per minute do the wheels make?__ rpm

4. ## Chemistry

Here are the effective nuclear charges, Zeff, for the valence electrons of four different atoms. 1.30, 1.95, 2.60, 3.25 In order, these values could belong to what list of elements? Sr, Ca, Mg, Be Be, Mg, Ca, Sr C, B, Be, Li (or) Li, Be, B, C Here are the

5. ## Chemistry

The minimum frequency of light needed to eject electrons from a metal is called the threshold frequency, ν0. Find the minimum energy needed to eject electrons from a metal with a threshold frequency of 5.48 × 1014 s–1. With what kinetic energy will

6. ## precalculus

A radio tower is located 450 feet from a building. From a window in the building, a person determines that the angle of elevation to the top of the tower is 29 degrees and that the angle of depression to the bottom of the tower is 22 degrees. How tall is

7. ## Precalculus

To estimate the height of a building, two students find the angle of elevation from a point (at ground level) down the street from the building to the top of the building is 33 degrees. From a point that is 300 feet closer to the building, the angle of

8. ## precalculus

Find cos(t) where the terminal ray of the angle t radians in standard position passes though the point (-4,-3).

9. ## Precalculus

Solve cos(x) = -0.44 on 0 (less than or equal to) x (less than) 2pi There are two solutions, A and B, with A < B Give your answers accurate to 3 decimal places

10. ## chemistry

Container A holds 767 mL of ideal gas at 2.50 atm. Container B holds 144 mL of ideal gas at 4.70 atm. If the gases are allowed to mix together, what is the resulting pressure?

11. ## Chemistry

Assuming that the smallest measurable wavelength in an experiment is 0.410 fm (femtometers), what is the maximum mass of an object traveling at 395 m·s–1 for which the de Broglie wavelength is observable?

12. ## Precalculus

Solve sin(x) = -0.36 on 0 le x lt 2pi There are two solutions, A and B, with A < B and A and B in radians to 4 decimal places.

13. ## Chemistry

A ground state hydrogen atom absorbs a photon of light having a wavelength of 93.77 nm. It then gives off a photon having a wavelength of 2630 nm. What is the final state of the hydrogen atom?

14. ## Precalculus Test

I have a precalculus test coming up and I'm not really understanding how to do everything. Please help. 1. Find the angle betweem 0 and 2pi which is coterminal to the angle -(7pi)/5. Now convert the angle you just found to degrees.

15. ## precalculus

Solve 7 cos(2 theta) = 7 sin^2(theta) + 3 for all solutions 0 less than or equal to theta less than 2pi. Solve 7 sin(2 w) - 4 cos(w) =0 for all solutions 0 le w lt 2pi

16. ## precalculus

Find all solutions for the equation 3cos(x)=cot(x). When do I use +2kpi? Is it only when I'm suppose to "find all solutions"? I got sin(x)=1/3. Is that correct?

17. ## precalculus

Solve the equation cos(2x)cos(x)+sin(2x)+sin(x)=1 for all values of x.

18. ## precalculus

Find the tan(x), the sin (x + pi) if it is known that cos (x)=.6 and that (3pi)/2 less than x less than 2pi. Find the sine (2x), the tan (2x), and the cos (x/2) if it is known that cos (x)=.6 and that (3pi)/2 less than x less than 2pi.

1. ## precalculus

thank you for your help! These problems get really confusing when they don't provide a picture.

posted on April 27, 2013
2. ## precalculus

Thank you for your help! My numbers were way off haha.

posted on April 15, 2013
3. ## precalculus

le= less than or equal to lt = less than I keep getting numbers that are not on the unit circle and then when I try to plug them into my calculator I'm getting really big numbers. Please help. I've tried looking in my book but there are no problems like

posted on April 15, 2013
4. ## precalculus

or would it be (-3/5)/(-4/5)

posted on April 10, 2013
5. ## precalculus

okay so if I was suppose to find tan (t)it would be tan= -3/-4?

posted on April 10, 2013