In similar cases decided yesterday, owners of one high-rise apartment agreed to pay $100,000 to daughters of a woman slain in the building and a jury awarded $43,000 to a woman whose 9-year-old daughter was sexually assaulted in another high-rise apartment.

Apartment security was at issue in both cases, which involved crimes committed in the Maryland suburbs.

In the first case, the owners of Presidential Towers on Metzerott Road in Adelphi, which advertises elaborate security arrangements, agreed to a $100,000 out-of-court settlement just as the case was about to go to the jury.

In the second case, decided by a Montgomery County jury late last night, the $43,000 was ordered paid to the 9-year-old's mother by management that was accused of failing to make every reasonable attempt to provide security for tenants.

That judgment involves the Oak Leaf Towers complex in White Oak, which changed its name from El Dorado Towers a month after the attack on the little girl in late 1977. El Dorado Towers was involved in a similar case in 1975 in which the partment owner and a furniture company were ordered to pay $1.3 million to the husband and two children of a woman who was raped and murdered by a furniture mover in the building.

In the $100,000 Presidential Towers settlement agreed to yestereday, jury foreman Elizabeth Hudak said she believed any jury award would have been lower.

Renee and Tamara Shepard sued Presidential Towers for negligence and breach of contract in a trial that began five days ago. Their mother, Vivian Jennings, was killed in the stairwell of the 16th floor of her apartment complex in February 1975 by an estranged boyfriend, Everett Powell. Powell is serving a life sentence for the murder at the state penitentiary in Baltimore.

Renee Shepard, 21, testified that on three occasions her mother had asked security guards and a desk clerk to be on the lookout for Powell and not to let him enter the apartment complex. Jennings was estranged from Powell, but he insisted on visiting her, according to the suit.

Willie Shepard III, Jennings' son, brought the suit on behalf of his sisters. He accused Presidential Towers of allowing the doors of the apartment complex to remain unlocked.

The complex advertises in its brochure that it has "security lock systems installed on each door, closed circuit television covering entrances and voice communications from the lobby desk to each apartment." Joseph Montedonico, the attorney for the group of New York City lawyers who own the complex, acknowledged that the doors of the apartment complex were unlocked.

Montedonico said tenants purposely left doors open because they didn't like them locked. Attorneys represented evidence that tenants repeatedly propped doors ajar or broke them. Eleven tenants testified they propped doors open to make it easier to bring in groceries or other items.

During the trial, an economist for the Shepards testified that Vivian Jennings' death cost her daughters $95,976 she would have given the girls, then 13 and 17, through their college years. He said her death had cost them $60,349 more for personal services she would have rendered like washing their clothes and cooking their meals.

According to court records, Shepard also charged that the one guard assigned to patrol the two 20-story buildings was not an adequate number of guards.

In agreeing to the settlements, the plaintiff's attorney, Allan Sosslau, said Presidential Towers denied negligence in the incident.

In the case decided by the Montgomery County Circuit Court jury last night, the mother of the 9-year-old girl who was sexually assaulted was awarded $37,000 in damages plus $6,000 for the girl's medical and psychiatric treatment.

The mother's attorney, Peter Mesitte, contended that the back door of the apartment building - then known as El Dorado Towers - was broken and unrepaired when the attack occurred on Thanksgiving 1977. He also termed the apartment complex a "sea of crime."

The girl was attacked as she entered the door and approached a stairwell. Her assailant has never been caught. Paul McCormick, attorney for the defendants, Lockwood Drive Co. and Zalco Realty Inc., argued that security measures aimed at barring intruders should not be at issue since it has never been proved that the assailant was an intruder. McCormick said he anticipates an appeal.

The child's mother, close to tears after hearing the verdict, said she and her daughter will move to the West Coast, where the girl will undergo psychiatric counseling.