# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 5 Search : exact
 exact   رزین   razinFr.: exact   1) Strictly accurate or correct; precise, as opposed to approximate. 2) The complete solution of an equation. For example, in the equation x2 = 7, the positive solution 2.646 is correct to three decimal places. The exact answer is x = 71/2. See also: → exact differential, → exact differential equation, → exact science, → accurate, → precise, → rigorous.From L. exactus, p.p. of exigere, literally "to drive out, thrust out," also "demand, finish, measure," from → ex- "out" + agere "drive, lead, act," → act.Razin "firm, solid, strong" [Dehxodâ, Steingass], Mid.Pers. razên "firm, strong, secure, solid." exact differential   دگرسانه‌ی ِ رزین   degarsâne-ye razinFr.: différentielle exacte   If N(x,y) is a → function of two → independent variables, then dN = (∂N/∂x)dx + (∂N/∂y)dy is the exact differential.→ exact; → differential. exact differential equation   هموگش ِ دگرسانه‌ای ِ رزین   hamugeš-e degarsâneyi-ye razinFr.: équation différentielle exacte   A → differential equation composed of → continuous  → differentiable functions for which certain conditions are fulfilled. The equation M(x,y)dx + N(x,y)dy = 0 is called exact if M(x,y) and N(x,y) are continuous differentiable functions for which the following relationship is fulfilled: ∂M/∂y = ∂N/∂x, and ∂M/∂y and ∂N/∂x are continuous in some region.→ exact; → differential; → equation. exact number   عدد ِ رزین   adad-e razinFr.: nombre exact   A value that is known with complete certainty. Examples of exact numbers are defined numbers, results of counts, certain unit conversions. Some examples: there are exactly 100 centimeters in 1 meter, a full circle is exactly 360°, and the number of students in a class can exactly be 25.→ exact; → number. exact science   دانش ِ رزین   dâneš-e razinFr.: science exacte   A field of study that admits especially precise predictions and rigorous methods of testing hypotheses, especially reproducible experiments involving quantifiable predictions and measurements.→ exact; → science.