Trigonometry Values Pi/10
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|  | (1) |
So we have
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|  | ||
|  | (2) |
and
 | (3) |
| |  | (4) |
| |  | (5) |
 | |  | (6) |
 | |  | (7) |
 | |  | (8) |
 | |  | (9) |
An interesting near-identity is given by
 | (10) |
.See also Decagon, Decagram- Robbins Equation
- Robbin's Inequality
- Robertson Condition
- Robertson Conjecture
- Robertson-Seymour Theorem
- Robin Boundary Conditions
- Robin's Constant
- Robinson Projection
- Robust Estimation
- Rodrigues Formula
- Rodrigues's Curvature Formula
- Rogers-Ramanujan Continued Fraction
- Rogers-Ramanujan Identities
- Rolle's Theorem
- Roman Coefficient
- Roman Factorial
- Roman Numeral
- Roman Surface
- Roman Symbol
- Romberg Integration
- Rook Number
- Rook Reciprocity Theorem
- Rooks Problem
- Room Square
- Root