2
Language: English Day: 1 S A B S C S AC = BC S AB C S P S PA = PB = PC n 3 n n 3 n (a, b, c) ab - c, bc - a, ca - b 2 2 2 n n ABC AB > AC Γ H F A M BC Q Γ HQA = 90 K Γ HKQ = 90 AB C K Q Γ KQH FKM

IMO 2015 Problems

Embed Size (px)

DESCRIPTION

International Mathematical Olympiad 2015, Chiang Mai, Thailand.

Citation preview

  • Language: English

    Day: 1

    r

    Pr s tt t st S ts t s r t rt

    ts A B S tr s t C S s tt AC = BC s tt S s trr r tr rt ts A B C S tr s t P S s tt PA = PB = PC

    tt r trs n > 3 tr sts st sst n ts

    tr trs n > 3 r tr sts trr st sst nts

    Pr tr trs (a, b, c) st trs s tt t rs

    ab c, bc a, ca b

    s r 2

    r 2 s tr t r 2n r n s t tr

    Pr t ABC t tr t AB > AC t ts rr H tsrttr F t t t tt r A t M t t BC t Q t

    t s tt HQA = 90 t K t t s tt HKQ = 90 sstt t ts A B C K Q r rt ts rr

    Pr tt t rrs trs KQH FKM r tt t tr

    s rs ts

    r s rt ts

  • Language: English

    Day: 2

    tr

    Pr r ABC s rr rtr O r t tr Atrsts t st BC t ts D E s tt B D E C r rt

    BC ts rr t F G t ts trst s tt A F B C G ts rr t K t s t trst t rr tr BDF t st AB t L t s t trst t rr

    tr CGE t st CA

    s tt t s FK GL r rt trst t t t X Pr tt X s

    t AO

    Pr t R t st r rs tr ts f : R R sts tqt

    f(x+ f(x+ y)

    )+ f(xy) = x+ f(x+ y) + yf(x)

    r r rs x y

    Pr sq a1, a2, . . . trs stss t ts

    1 6 aj 6 2015 r j > 1

    k + ak 6= + a r 1 6 k <

    Pr tt tr st t st trs b N s tt

    n

    j=m+1

    (aj b)

    6 10072

    r trs m n sts n > m > N

    s rs ts

    r s rt ts