Which characteristics of crystal faces define crystal systems?
angle
color
number
size
hardness

a compound light microscope is used to magnify objects in steps.  

hope it

answer;

-vessels in the chest

the diagnosis of angina pectoris literally means "vessels in the chest"

explanation;

-angina pectoris is the medical term for chest pain or discomfort due to coronary heart disease.it is the chest pain due to an inadequate supply of oxygen to the heart muscle. the pain is typically severe and crushing, and it is characterized by a feeling of pressure and suffocation just behind the breastbone.

agina pectoris is caused by reduced blood flow to your heart muscle. the blood carries oxygen, which the heart muscle needs to survive. when the heart muscle isn't getting enough oxygen, it causes a condition called ischemia