principal plane

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noun Optics.

a plane that is perpendicular to the axis of a lens, mirror, or other optical system and at which rays diverging from a focal point are deviated parallel to the axis or at which rays parallel to the axis are deviated to converge to a focal point.

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Question 1 of 7

Which sentence is correct?

His boss, whom he admires, is waiting to meet with him about the big project.

His boss, who he admires, is waiting to meet with him about the big project.

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Words nearby principal plane

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How to use principal plane in a sentence

Chérif was arrested in Paris in January 2005 as he was about to board a plane to Damascus along with a man named Thamer Bouchnak.
France Mourns—and Hunts|Nico Hines, Christopher Dickey|January 8, 2015|DAILY BEAST
As we waited for my plane to come in, we stayed silent for a long time.
The Story Behind Lee Marvin’s Liberty Valance Smile|Robert Ward|January 3, 2015|DAILY BEAST
And then I got on a plane, and guess what was playing: I Never Sang for My Father.
The Story Behind Lee Marvin’s Liberty Valance Smile|Robert Ward|January 3, 2015|DAILY BEAST
“Call me when the plane leaves the ground,” she said, in a tone that implied she knew her husband well.
Mario Cuomo, a Frustrating Hero to Democrats, Is Dead at 82|Eleanor Clift|January 2, 2015|DAILY BEAST

On Monday, Soelistyo had jolted relatives as well as searchers by suggesting that the plane could be “at the bottom of the sea.”
Wreckage, Bodies of AirAsia Crash Found|Lennox Samuels|December 30, 2014|DAILY BEAST
This is the first and principal point at which we can stanch the wastage of teaching energy that now goes on.
The Salvaging Of Civilisation|H. G. (Herbert George) Wells
"The Smoker," and "Mother and Daughter," a triptych, are two of her principal pictures.
Women in the fine arts, from the Seventh Century B.C. to the Twentieth Century A.D.|Clara Erskine Clement
It is the principal waste-product of metabolism, and constitutes about one-half of all the solids excreted—about 30 gm.
A Manual of Clinical Diagnosis|James Campbell Todd
The principal room or "hall" will accommodate about 1,000 persons, the remaining portion of the premises being let off in offices.
Showell's Dictionary of Birmingham|Thomas T. Harman and Walter Showell
Thomas Barnes, principal editor of the Times newspaper, died in London, aged 56.
The Every Day Book of History and Chronology|Joel Munsell