The of a lens or mirror is a rotational symmetry axis of the surfaces.

Optical axis

Step-by-step explanation:

Optical axis is the rotational symmetry axis of the surfaces.

A line with a certain degree of rotational symmetry is called as the optical axis in an optical system.

It is the straight line that passes through the geometric center of the lens and joins two curvature centers of its surfaces.

It is also called as the principal axis.

answer: the value should be used for i in the formula of calculation the monthly payment , the interest rate per period is 0.85.

step-by-step explanation:

the given rate of interest i= 85%

in calculating the monthly payment for a loan with an interest rate compounded monthly, the value of the interest rate per period we use in the formula must be in decimal form.

to convert it in decimal, we divide it by 100, we get

hence, the value should be used for i in the formula of calculation the monthly payment , the interest rate per period is 0.85.

the answer will be b x² +x-1

step-by-step explanation: