A sequence diagram of three messages — SYN, SYN-ACK, ACK — where every arrow's slope is a delay and the numbers on the arrows are the formula, so picture and formula are the same three facts. Evidence: slow start after the handshake; the ladder is one round trip across four distances.
Three little shouts before you talk
Two friends want to talk across a playground. The first shouts 'Can you hear me?' The second shouts back 'Yes! Can you hear ME?' The first shouts 'Yes!' Now they both know the other one can hear, so they start talking for real. Three shouts, and only then the conversation — that's the handshake.
Nobody starts the story until both know the other can hear.
SYN(x) → SYN-ACK(y, x+1) → ACK(y+1) ⇒ ESTABLISHED
Same rack
datacentre
100 µS
Same city
fibre
5 MS
Cross-continent
fibre
70 MS
Satellite
GEO hop
600 MS
Round-trip bars are log-scale — each step is 10×; a handshake costs one and a half of them