Mongge

perpendicularidade

Carme_Castelao
 
 637
 
Answer
Solution

}

vα

hα

r2

r1

α

r

s

t

u

r2

r1

s2

s1

t2

t1

u2

u1

α

β

δ

r

vα

hα

r2

r1

vβ

hβ

hδ

vδ