Final answer:
In triangle RST, if angle R is acute, it means that angle R is less than 90 degrees.
Step-by-step explanation:
In triangle RST, if angle R is acute, it means that angle R is less than 90 degrees.
An acute angle can be visualized as an angle that is less than a right angle, like the angle formed by the hands of a clock at 4 o'clock.
So, if angle R is acute, its measure must be less than 90 degrees.
Learn more about Triangle angles