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The slope of the rake is measured by the number of horizontal units it takes for one vertical unit measured in the direction of the slope, or by the equivalent percentage. A rake of one horizontal unit to one vertical unit (1 in 1), would give an angle of 45° from the horizontal. Rakes of 1 in 18 (5.56%) to 1 in 48 (2.08%) were more common. Modern stages are constructed with no slope, and the majority of existing raked stages have been renovated into unraked arrangements.
Converting the rake ratio to an angle requires the application of some basic trigonometry. The angle in degrees = arcTan (opposite/adjacent), where opposite = the rise, normally 1 and adjacent = the distance this rise occurs over. Example: for a rake of 1:18; arcTan(1/18) = 3.18°
Theatres constructed after the beginning of the 20th century feature a raked audience section. This change back to the method of construction seen in Greek and Roman theaters, (flat stage and terraced audience) was effected due the difficulty encountered when one tries to walk across a sloped surface, which had resulted in unnatural movement patterns to avoid the appearance of limping caused by the non-level surface.
Raked stages can still be seen in many opera productions, where a temporary raked acting surface is built over a theatre's permanent flat stage. Creating a raked stage can also assist set designs requiring forced perspective.
On a raked stage an actor who is farther from the audience is higher than an actor who is closer to the audience. This led to the theatre positions "upstage" and "downstage," meaning, respectively, farther from or closer to the audience.
The practice of "upstaging" other actors comes from the practice of moving to a more elevated position on the rake, causing the upstaged actor (who stays more downstage) to turn his back to the audience to address the cast member. The term "upstaging" also has since taken on the figurative meaning of an actor unscrupulously drawing the audience's attention away from another actor.