Mathproblem

[henrik21]

Let v be the pointy angle (measured in radians) between the x-axis and the line through (0,0) and (3,4). Then what is sin(v - pi/2).

I get the answer to the same as -cos(3/5) but i need the answer in the form a/b

 

[chuckywang]

sin(v-pi/2) = -cos(v) = -3/5

 

[henrik21]

Got another one here, cos(7x - 2p/3) = - sqr(3)/2

The solutions can be written on the form (4 5)pi/p + 2npi/q where n = any number (non decimal) and p and q are specific numbers, what is p and q?

This is how far I've made it on my own: -cos(-7x) +sqr(3)*sin(7x) = -sqr(3)

 

[Goosemaster]

pointy angle?

LOFL