a,
Chu vi MPQ = MP + MQ + PQ = MP + MQ + PK + QK = MP + PI + MQ + QH = MI + MH = 2MI (không đổi)
b
[tex]\widehat{IOP} = \widehat{POK}[/tex]
[tex]\widehat{KOQ} = \widehat{QOH}[/tex]
=> [tex]\widehat{POK} + \widehat{KOQ}[/tex] = [tex]\widehat{IOP} + \widehat{QOH}[/tex] = 2[tex]\widehat{IOH}[/tex]
c,
PQ < MP + MQ
=> PQ + QH + IP < MP + MQ + QH + IP = MI + MH
=> 2PQ < MI + MH