6.5 Complex Human Ecosystems: 1. 6.30 The Gamble of Investment? 1.55 Maths: Least Squares. 7.20 Invention is not Enough. 7.45 Roman Interior Decoration.

The last of 12 programmes Trigonometry 11
Solving three-dimensional trigonometry problems is a process of abstraction. The trees, cliffs, rivers and mountains commonly appearing in such problems have to be replaced by right-angled triangles. Once all the important information is assembled, sine, cosine and tangent will do the rest. Presented by NORMAN GOWAR (OU)

The Embassy
World Professional Championship from The Crucible Theatre, Sheffield
Third day
STEVE DAVIS is still the favourite to win this title for the second time even after the disaster of the first round last year when TONY KNOWLES caused the upset of the season, with his 10-1 victory. REX WILLIAMS or FRED DAVIS are the likely opposition. DENNIS TAYLOR will be hoping for a better result against SILVANO FRANCISCO than he achieved last year when, as the number five seed, he was beaten 10-7,in another shock result. DAVID vine introduces live coverage and highlights.
Commentators TED LOWE
JACK KARNEHM and CLIVE EVERTON

Do hospital doctors and patients speak the same language? This film tries to capture day-to-day life in two hospitals, particularly the ways in which language is used between doctor and patient, and doctor to doctor, as a way of sharing and restricting knowledge.
Producer RICHARD ARGENT
A BBC/Open University production

The first of five programmes written and presented by John FitzMaurice Mills 1: Bygones
A zebra skin, a pair of antlers, Tunbridge Ware , a period doll, a feather fan and a leather box - all highly collectable but in need of attention. JOHN FITZMAURICE MILLS demonstrates a few simple remedies which you can use safely at home.
Assistant producer AMANDA THEUNISSEN Producer CHRISTOPHER LEWIS BBC Bristol

' Black Britons are suffering a discrimination and racial disadvantage deriving partly from a deep unconscious prejudice in the rest of the community, which we've not yet exposed and killed. I think it's true of almost everybody.' (LORD SCARMAN) ' An unintentional racism remains embedded in our culture and institutions - not least the school system. (BRENDA THOMSON) Bradford teacher)
A film which investigates the nature of British attitudes towards ethnic minorities, raising questions particularly about the role of schools in preparing the next generation for life in a multi-racial society.
Narrated by MICHAEL DEAN
A chilling documentary (THE GUARDIAN) A provocative but necessary programme
(THE TIMES)
Book, Multi-Cultural Education, £3.75 from booksellers

with subtitles, followed by Weather

Frame of the Day and further coverage

between Arthur Marshall
Maureen Lipman , Roy Marsden and Frank Muir
Hannah Gordon , Me vyn Bragg Referee Robert Robinson
Devised by MARK GOODSON and bill tooman Directed by JOHN BISHOP Producer PAUL CIANI

Johnny Mathis in concert at the Dominion Theatre, London and in conversation with Noel Edmonds

First of three silver anniversary programmes recorded during his last tour of Britain.
(Repeat)

The Embassy
World Professional Championship from The Crucible Theatre, Sheffield up-to-aate reports

Sixty Minutes to Meltdown
4.0 am, 28 March 1979: Three Mile Island Nuclear Power Station, Pennsylvania. Alarms go off in the control room: within seconds, the world's most notorious nuclear power accident has begun. A leak develops in the cooling system: temperature and radiation levels begin to rise. For the next few hours operatives struggle frantically to understand what's happening and to prevent the nuclear cone from being uncovered. They fail, and it begins to melt. At the end of the day, they are left with a ruined nuclear power station, and a lot of unanswered questions. This film chronicles the minute-by-minute events of the TMI disaster in a dramatised hearing based on the various official inquiries and reports that followed it. It reveals a story of design faults, failures of communication and human error. Hearing the testimony one might conclude, as some did at the time. that Three Mile Island was an accident waiting to happen.
Horizon editor GRAHAM MASSEY Produced for WGBUTV Boston by BRIAN KAUFMAN
(Postponed from 28 March)

TERRY GRIFFITHS , the 1979 Champion and current United Kingdom Champion, makes his first appearance this year, and EDDIE CHARLTON completes his first-round match.
DAVID VINE introduces the action

John Tusa , Peter Snow and Donald MacCormick , with Joan Bakewell and Linda Alexander , present reports, interviews and analysis.

DAVID VINE with further coverage.