Alan

The online normal distribution calculator at http://stattrek.com/online-calculator/normal.aspx should enable you to answer this.

csc ϕ = 1/sin ϕ   so   sin ϕ (csc ϕ − sin ϕ) →  sin ϕ (1/sin ϕ - sin ϕ)  →  1 - sin² ϕ  →  cos² ϕ

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Type asin(1/3)    asin is the same as sin^-1.  Press the 2nd button first to show asin.

It depends what you want to find the surface area of!!  The formula for the surface area of a sphere is different from that of a cube, for example.

You could use the calculator on the home page here:

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Frictional force is given by coefficient of friction times normal force.

Hence frictional force = 0.17*2.6*9.8 N  or  ≈ 4.33N

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As x → c f(x) gets smaller than 1 at some point and g(x) gets larger than 1 at some point.  

(a) A number smaller than 1 raised to a power larger than 1 is even smaller then the small number, so the combination tends to zero.

(b) With g(x) tending to -infinity, you have the combination tending to 1/0 (i.e. tending to infinity).

If f(x) = 8 – 10x and g(x) = 5x + 4, what is the value of (fg)(–2)?

g(-2) = 5*(-2) + 4 = -6

(fg)(-2) → f(g(-2)) = 8 - 10*(-6) =  68

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If you mean what angle has a tan of 0.0512 you can use the calculator on the home page: press 2nd atan 0.0512 (you should get 2.930984565584°  or ≈ 2.93°).

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Let the height of the shorter building be h metres and the width of the street be w metres.

tan(38°) =  (h + 30)/w              (1)

tan(23°) =  h/w                        (2)

Subtract (2) from (1) to get    tan(38°) - tan(23°) = 30/w   so  w = 30/(tan(38°) - tan(23°))

I'll leave you to crunch the numbers.