Final answer:
The appropriate angle to use when preparing a blood smear is 30°. Holding the spreader slide at this angle ensures an even and thin smear, allowing for proper visualization of blood cells under a microscope.
Step-by-step explanation:
The appropriate angle to use when preparing a blood smear is 30°.
When preparing a blood smear, the angle at which the spreader slide is held in relation to the slide with the blood sample is important. Holding the spreader slide at a 30° angle allows for an even and thin smear to be created, ensuring that the blood cells are properly distributed and visible under a microscope.