Cyril Lang, the Montgomery County English teacher suspended last year for using works by Aristotle and Machiavelli in his 10th grade classes, lost his appeal to the Maryland State Board of Education yesterday.

In a unanimous ruling, the state board said that the Montgomery County Board of Education had been justified in finding Lang, 56, guilty of misconduct and insubordination for defying the orders of his principal not to include questions on the works in his final exam. But the state board cut the length of the suspension from 28 to 15 working days, a loss in salary of about $1,760 instead of the $3,293 originally imposed.

The ruling followed a recommendation by hearing examiner Elizabeth L. Nilson who found that county policies did not prohibit Lang from presenting the works as "enrichment materials." But Nilson said the teacher could not include them in an exam, because that would require students to master works that were not part of the approved curriculum.

The case, which drew nationwide attention, involved Aristotle's "Poetics" and Machiavelli's "The Prince," which Montgomery County curriculum officials had decided were too difficult for 10th graders. Lang taught them anyway, citing academic freedom, but the state board dismissed this claim, saying the case turned on the "power of the school system to enforce" its curriculum decisions.

At the time of the dispute Lang was teaching at Charles W. Woodward High School in Rockville. Since last September he has been at Bethesda-Chevy Chase High School.