The true anomaly and the eccentric anomaly are related as follows. Using the formula for "r" above, the sine and cosine of "E" are found in terms of "θ":  Hence,  Angle "E" is therefore the adjacent angle of a right triangle with hypotenuse , adjacent side , and opposite side . Also,  Substituting cos "E" as found above into the expression for "r", the radial distance from the focal point to the point "P", can be found in terms of the true anomaly as well:  The eccentric anomaly "E" is related to the mean anomaly "M" by Kepler's equation:  This equation does not have a closed-form solution for "E" given "M". It is usually solved by numerical methods, e.g. the Newton–Raphson method.