Question

What is the distance between `(4 ,( - pi)/8 )` and `(-1 ,( 3 pi )/2 )`?

Answer 1

`P_1P_2~~4.47`

Explanation:

Use formula `P_1P_2=sqrt(r_1^2+r_2^2-2r_1r_2cos(theta_2-theta_1))`

`r_1=4,theta_1=-pi/8 and r_2=-1,theta_2=(3pi)/2`

`P_1P_2=sqrt(4^2+(-1)^2-2(4)(-1)cos(((3pi)/2)-(-pi)/8)`

`=sqrt(16+1+8cos((13pi)/8)`

`=sqrt(17+8cos((13pi)/8))`

`P_1P_2~~4.47`