Question

Do you know this?
What are these
​

Answer 1

The Greek letters you are most likely to see for angles are α (alpha), β (beta), γ (gamma), δ (delta), and θ (theta). And of course you'll be using π (pi) all the time.

Answer 2

$\huge\bf\red{Answer}$

$yes \: i \: know...$

Alpha radiation is the name for the emission of an alpha particle in fact an helium nuclei, beta radiation is the emission of electrons or positrons , and gamma radiation is the term used for the emission of energetic photons. ... At that time, nuclei, electrons and photons were unknown.