write 4R+9U in polar form

do you mean 4 right and 9 up?

Like 4 i + 9 j
if so
r = sqrt (16 + 81) = sqrt (97)
angle above x axis is theta
theta = tan^-1 (9/4)

@Damon Yes, 4R means go four to the right (because its positive) and 9U means go nine up from the four (because 9 is positive)

strangest notation I ever saw ...

To write 4R + 9U in polar form, we need to convert the rectangular form into polar form.

In order to do that, we need to know the values of R and U. R represents the real component, and U represents the imaginary component.

If you have the values of R and U as given in the expression, you can use the following formula to convert rectangular form to polar form:

r = √(R^2 + U^2) - the magnitude or modulus of the complex number
θ = atan(U/R) - the argument or phase angle of the complex number

Once you calculate the values of r and θ, you can express the complex number in polar form as r(cos(θ) + i*sin(θ)), where r is the magnitude and θ is the argument.

So, substitute the given values of R and U into the formulas to find the magnitude and argument.

Then, write the expression in polar form as r(cos(θ) + i*sin(θ)).