Alan

This becomes:  \(7(31+19)\rightarrow7\times31+7\times19\rightarrow217+133=350\)

sin(theta) = cos(90° - theta) = 1/sec(90° - theta)    

Note that cos(90° - theta) = cos(90°)cos(theta) + sin(90°)sin(theta) = 0*cos(theta) + 1*sin(theta) = sin(theta)

Density is mass/volume, so calculate the volume:  vol = 3*6*4  (you haven't provided the units!) and mass = 80 (again you haven't provided the units) so density = 80/(3*6*4) = 1.111... mass units per cubic length units.

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Any line perpendicular to y = (2/3)x + 9 will have slope -3/2, so its equation will be y = -(3/2)x + c where c is a constant, different for each line.

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Assuming there is no air drag then distance = (1/2)*9.8*4^2 m = 78.4 m  where acceleration of gravity is taken to be 9.8 m/s^2).

cos(pi)  or (cosine(pi))  is -1

It's  \(R=\frac{r1r2}{r1+r2}\)

Looks like add 3, subtract 2, add 3 subtract 2, so the next one would be add 3 to 4 giving 7.

Use p₁V₁/T₁ = p₂V₂/T₂ where p is pressure, V is volume and T is absolute temperature (i.e. 27°C must become 300K and 30° must become 303K)

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See answer at: http://web2.0calc.com/questions/dice-rolling