The following was aming actions taken at the May 2 meeting of the Arlington County Board. For more information, call 558-2261.

HYDE PARK PLAZA APPROVED -- The board approved a request by Washington Corp. to build a $65 million office-retail complex on a 4 1/2-acre tract near the Ballston Common shopping center. The project, which will consist of two eight-story office buildings and two two-story buildings for retail businesses, will be constructed on land bounded by North Glebe Road, North Henderson Road, North Thomas Street and North Carlin Springs Road.

Washington Corp. also has promised to build a fifth building on North Thomas Street to house the elderly, one of Arlington's fastest-growing populations.

County officials have said that housing for the elderly is a high priority. Between 1970 and 1980, the number of county residents over the age of 65 increased by 30 pecent while the county's total population dropped 12 percent.

The board approved a tentative height limit for the fifth building of 75 feet, or about eight stories. The developer still must come back to the board with a final site plan for the building.

Construction of the office-retail complex could begin in late 1988 and be complete within 15 months.