Final answer:
The horizontal plane is perpendicular to both the coronal (frontal) and sagittal planes and is located at right angles to them.
Step-by-step explanation:
The question refers to the various anatomical planes of the human body, which include the sagittal plane, coronal (frontal) plane, and transverse (horizontal) plane. These planes are used to describe locations and orientations within the body. The sagittal plane divides the body into right and left portions, which can be an exact division down the middle known as the midsagittal plane or a division into unequal parts known as a parasagittal plane.
The coronal plane, also called the frontal plane, divides the body into anterior (front) and posterior (back) sections. Lastly, the transverse plane cuts across the body horizontally, dividing it into upper and lower portions. When the question asks about the horizontal plane passing 'at right angles to the --- and --- planes,' the missing words are 'coronal' and 'sagittal' since the transverse plane is perpendicular to both.
The horizontal plane, known as the transverse plane, is perpendicular to both the coronal (or frontal) and sagittal planes. It divides the body into upper and lower sections, contrasting with the coronal plane's front-back division and the sagittal plane's right-left division.