President Reagan is scheduled to arrive here Tuesday on a five-day Latin American visit that officials here said they perceive as one of a growing number of signs that regional relations with the United States have been jolted into a new and decidedly different direction.

Brazil and many other South American countries reached a high point in tensions with the United States this year because of Washington's support for Britain against Argentina in the Falkland Islands conflict and what were regarded here as punishing U.S. economic policies.

But with Reagan's visit to Brazil and three other Latin American countries, officials here say they perceive a U.S. willingness to shift focus.

"There is a show of good will," said one Brazilian government official here. "It is a broader approach, more sensitive to Third World interests."

For Brazil and South America's other powers, the U.S. effort to repair relations began with its support of the U.N. resolution urging negotiations between Britain and Argentina and with Reagan's sudden decision to travel to Brazil, Colombia, Costa Rica and Honduras.

But more important, officials here said, has been a new strategy by the Reagan administration to help the region's economies through their worst troubles since the 1930s, a plan expected to be a key theme of Reagan's trip.

Once perceived here as insensitive to Brazil's mounting trade problems and $80 billion foreign debt, U.S. officials have now indicated that they will support Brazilian efforts to raise new funds and perhaps plug gaps with direct treasury loans.

The U.S. presidential visit here and to the financial center of Sao Paulo is viewed by Brazilians as a clear vote of confidence in their economic management.

In Brazil, where economic themes have recently grown to be a crucial factor in foreign relations, the prospective U.S. stress on economic assistance is regarded as a timely--and essential--shift from policies that have distanced the two countries since the late 1970s.

Some analysts believe that the U.S. involvement in Brazilian finances, and Brazil's strong need for continued U.S. help, will propel Brazil toward closer alignment with Washington and its broader regional interests. In recent years, while emerging as Latin America's economic superpower, Brazil has shaped an increasingly independent foreign policy stressing relations with Third World nations and North-South issues.

But despite the optimism surrounding Reagan's arrival, most officials and analysts believe that Brazil's military government will most likely stick to long-term policies that have distanced them from direct alignment with the United States.

Faced with possible U.S. expectations of greater strategic alliance, Brazilian officials answer that closer economic cooperation after Reagan's visit will help preserve both U.S. investments and broader interests in the region.

"It is a matter of enlightened self-interest for the United States," an official here said. "If Brazil were to become destabilized, it would be as serious for the United States as it would be for Brazil."

Throughout South America, Reagan's visiting delegation could find governments that have similarly sought to maintain distance from the United States following U.S. involvement in Central American conflicts and the Falkland Islands war.

This year, both Venezuela and Colombia have moved to join the Nonaligned Movement, and Peruvian President Fernando Belaunde called off a scheduled visit to Washington this month to signal unease with the Reagan administration.

In Colombia, where Reagan will arrive from Brazil, officials of the new Conservative government of Belisario Betancur are expected to stress to Reagan and U.S. officials that Latin governments have been alienated by what they see as an increase in superpower competition on the continent.

In addition, Colombian officials say the United States has weakened the Organization of American States by failing to maintain neutrality in the Falklands conflict and by stressing bilateral relations.

While these complaints are shared by many South American governments, it has been the economic crisis -- and the U.S. role in it -- that has increasingly emerged as a central issue since the end of the South Atlantic fighting in June.

As the U.S. recession has continued, almost every South American country has seen the prices of its primary export products plunge on metals and commodities markets and the volume of its manufactured sales drop off. In most of the region, this recessionary force has been greatly worsened by large foreign debts and the inability of governments to meet payments without enforcing strict internal economic discipline, such as cuts in imports.

Many Latin governments have come to blame the Reagan administration for high interest rates, with the double effect of depressing markets and raising foreign debt costs, and U.S. protective measures against subsidized exports to the U.S. market.

Nowhere have the tensions been worse than in Brazil. U.S. trade is crucial to Brazil's economy. The United States is the leading customer for Brazilian exports -- taking more than 19 percent of the total in the first quarter of this year -- and it provides about one-third of Brazil's non-oil imports. The total trade was $7.5 billion last year, but this year, 18 Brazilian products worth $1 billion have been investigated by U.S. authorities on dumping charges.

Brazil this year found its attempts to subsidize exports stiffly opposed by U.S. officials and its sources of new foreign financing threatened by U.S. efforts to taper off contributions to organizations such as the World Bank.

In response, President Joao Figueiredo charged in a speech in September at the opening of the U.N. General Assembly that "the present economic policy of the great powers is destroying riches" and that restrictions on trade and lending threatened to touch off a global economic collapse.