If `D ,Ga n dR` denote respectively the number of degrees, grades and radians in an angle, then (a) `D/(100)=G/(90)=(2R)/pi` (b) `D/(90)=G/(100)=R/pi` (c) `D/(90)=G/(100)=(2R)/pi` (d) `D/(90)=G/(100)=R/(2pi)`

Explanation

To solve the problem, we need to establish the relationships between degrees (D), grades (G), and radians (R) in terms of a common angle measurement.

### Step-by-Step Solution:

1. **Understanding Degrees:**
- We know that \(90\) degrees is equal to \(1\) right angle.
- Therefore, \(1\) degree can be expressed as:
\[
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