Resplendent theater from the Royal Shakespeareans

Broadway is reveling in one of the glories of this or any other theatrical season: a visit from the Royal Shakespeare Company in a repertory consisting of Shakespeare's ''Much Ado About Nothing'' and Rostand's ''Cyrano de Bergerac,'' both directed by Terry Hands. The engagement at the Gershwin Theatre runs through Dec. 16. Much Ado About Nothing Comedy by William Shakespeare. Directed by Terry Hands.

It would be hard to imagine a more ravishing spectacle than the arrangement of gold-embossed silhouettes and transparencies devised by designer Ralph Koltai for ''Much Ado About Nothing.'' A raked stage provides a gleaming black surface for the extravagent comedy that passes across it.

Resplendent in the Cavalier finery created by costume designer Alexander Reid , the Royal Shakespeare Company players act the comedy with bravura style and buoyancy. In high-comedy terms, the misogynous Benedick (Derek Jacobi) and the declared spinster Beatrice (Sinead Cusack) must be tricked into realizing their mutual ardor. The counterplot concerns a villainous machination to prove that the blameless Hero (Clare Byam Shaw) is unworthy of her suitor, young Count Claudio (Christopher Bowen).

The joy of the performance springs from its tremendous zest and spirit. Mr. Jacobi and Miss Cusack conduct the Benedick-Beatrice ''merry war'' with infectious relish and resolute determination. No quarter is asked and none given. Mr. Jacobi's Benedick is such a fine and foolish fellow that his famous conclusion (''Nan is a giddy thing'') proves not only hugely funny but eminently sensible. Miss Cusack cherishes Beatrice's independence, witty tongue, and compulsion ''to speak all mirth and no matter.'' But the actress also touches the heart of the role, as in when Beatrice promises herself to requite Benedick's love - ''taming my wild heart to his loving hand.''

The foul intrigue against Hero is handled in the prevailing spirit of romantic make-believe. John Carlisle's Don John is a self-declared, plain-speaking villain of comedy. Mr. Bowen and Miss Byam Shaw dutifully persevere through the plot's artifices. Uncovering the slander against Hero involves some of those hilarious low-comedy scenes in which actors like Christopher Benjamin (Dogberry), Jimmy Gardner (Verges), and their fellows of the Watch have a field day. The acting standard is sustained throughout a company that includes Edward Jewesbury and Jeffery Dench (brothers Leonato and Antonio), Ken Bones (Don Pedro), Geoffrey Freshwater and John Bowe (the varlet pair), and George Parsons (Friar Francis), to name a few.

The visual effects of Mr. Hands's light plot range from mysterious chiaroscuro to blazing sunshine. As a director of comedy, he enjoys sight gags fully as much as painterly stage pictures. Nigel Hess's lovely incidental music includes passages for solo cello, song settings, and dance tunes for courtly measures. The pace of the light fantastic quickens in the finale, which climaxes a glorious homage to Shakespeare, showmanship, and theatrical magic. Cyrano de Bergerac Play by Edmond Rostand. Translated and adapted by Anthony Burgess. Directed by Mr. Hands.

The Royal Shakespeare celebrates Rostand's luxuriant romantic drama with a production on the grand scale and in the grand manner. Mr. Jacobi's makeup for Cyrano's legendary nose may be somewhat modified, but the fiery Gascon's wit, fervor, and gallantry are as proudly displayed as his triple white plume. Mr. Jacobi handles Cyrano's wordplay and swordplay with extravagant ease in a thrilling tour de force performance. But this splendid actor grasps also the bitterness, hurt, and loneliness of a hero who lives for a love that is returned too late.

As staged by Mr. Hands in the Anthony Burgess translation/adaptation, ''Cyrano de Bergerac'' plunges the spectator into the teeming world of 17 th-century Paris. When the play starts, attendants are lighting the candles of the huge candelabra soon to be raised over the gathering onstage audience of grandees and hoi polloi. Here it is that Cyrano first displays the nature of his intransigence as he makes good his threat to drive the offending tragedian, Montfleury, temporarily from the stage. Here, too, in a celebrated passage, Cyrano wins a duel as he improvises a rhyme.

Mr. Burgess's verse adaptation gives a kind of modern tone to an old-fashioned period romance - yet without damaging its essential dignity and genuineness. Mr. Jacobi and his colleagues grasp these essential qualities, which permeate the production from the bustle of opening scenes to the poignancy of the autumnal finale in which Roxane (Miss Cusack) discovers the truth about the two men who have loved her.

Meanwhile, the audience has been treated to all the play's essential incidental scenes and extravagant set pieces. The comedy in the poet-baker Ragueneau's pastry shop gives way to the leaf-enshrouded balcony scene in which Cyrano ardently woos Roxanne for the dumb but handsome Christian (Tom Mannion). Roxanne's visit to the battlefield at the siege of Arras combines romantic exposition, dramatic incident, and a glorious display of stage pyrotechnics.

In the final convent scene, 15 years after the main events, Roxanne forces the dying Cyrano's confession of love. It is there that Cyrano makes his last, fierce thrusts at the enemies against which he has fought: lies, compromise, prejudice, cowardice, and stupidity. In this cri de coeur, Mr. Jacobi caps a performance whose magnificence rests in its true humanity.

The vital elements of romantic truth characterize the production. They are strongly evident in Miss Cusack's spirited Roxanne and in the attractive earnestness of Mr. Mannion's Christian.

Other principals in an enormous and excellent cast include Mr. Bowe (the faithful Le Bret), Mr. Carlisle (Le Comte de Guiche), Pete Postlethwaite (the benign Ragueneau). Mr. Jacobi and the Royal Shakespeare Company have honored a great romantic hero with a great revival.