http://img37.imageshack.us/img37/1471/problem604.png Let K is the projection of B over AE and L is the projection of E over AB ( see picture) We have area(GAEF)=Area(ABH)+10=AE .BK= AB. EL= 2.* Area(ABE)=Area(ABCD) but Area(ABCD)=x+ Area(ABH) So x=10 Peter Tran
Extend GF and DE to meet at K ∆AGB≡∆EFK Using notation (…) for area (EFK) = (AGB) = 3 (BHEK) = 7 + 3 = 10 Denote (HCE) by y (BCK) = 10 + y Next ∆ADE ≡ ∆BCK (ADE )= (BCK) x+ y = 10 + y x = 10
Draw altitudes h1 from D to AH, h2 from B to AE S(ABCD) = (AH)(h1), S(AEFG) = (AE)(h2) From similarity (h2)/(h1) = (AH)/(AE) => h2 = ((AH)(h1))/(AE) => S(AEFG) = (AH)(h1) => S(ABCD) = S(AEFG) => x = 10
http://img37.imageshack.us/img37/1471/problem604.png
ReplyDeleteLet K is the projection of B over AE and L is the projection of E over AB ( see picture)
We have area(GAEF)=Area(ABH)+10=AE .BK= AB. EL= 2.* Area(ABE)=Area(ABCD)
but Area(ABCD)=x+ Area(ABH)
So x=10
Peter Tran
Extend GF and DE to meet at K
ReplyDelete∆AGB≡∆EFK
Using notation (…) for area
(EFK) = (AGB) = 3
(BHEK) = 7 + 3 = 10
Denote (HCE) by y
(BCK) = 10 + y
Next ∆ADE ≡ ∆BCK
(ADE )= (BCK)
x+ y = 10 + y
x = 10
Draw altitudes h1 from D to AH, h2 from B to AE
ReplyDeleteS(ABCD) = (AH)(h1), S(AEFG) = (AE)(h2)
From similarity (h2)/(h1) = (AH)/(AE) => h2 = ((AH)(h1))/(AE)
=> S(AEFG) = (AH)(h1) => S(ABCD) = S(AEFG) => x = 10