See Explanation
Step-by-step explanation:
1)
[tex] d = r. t\implies r = \frac{d}{t} \\
d = r. t\implies t = \frac{d}{r} \\[/tex]
2).
[tex] C = 2\pi.r\implies r = \frac{C}{2\pi} \\
C = 2\pi.r\implies \pi = \frac{C}{2r} \\[/tex]
Answer:
2.
A. r=d/t
B. t=d/s(r)
3.
A. r=c/2(pi)
B. (pi)=c/2r
Pretty easy once you have mastered Algebra and Geometry.
