Math Challenges

Wednesday, August 30, 2006

Problem of the Week 2 Update

Two correct solutions were received. Congratulations to Mr. Isaiah Duazo an ECE student of Rizal Technological University and Mr. Jobert Gimeno an ECE student of PUP Sta. Mesa for submitting the correct solutions.

Solution by Isaiah Duazo:

tan A = 22/7
let A is equal to B + D
tan A = TAn (B + D)
(1) Tan (B + D) = (Tan B + Tan D)/[1 - (TAn B)(Tan D)]

Let the length of the altitude be h:

Tan B = 3/h
TAn D = 17/h

Substituting the value of Tan A, Tan B, and Tan D to Equation 1 and solving for h:

h = 11 units

Area of triangle = (base)(height)/2 = (20)(11)/2 = 110 square units

2 Comments:

  • Sir Zarco. . .
    nakuha ko na p0h ung answer. . .
    tanA = 22/7
    let x: be the base angle of the side whose length is 17.
    let y: be the base angle of the side whose length is 3.
    Let s be the perpendicular side :
    therefore: x+y=A
    tanx=17/s ;tany=3/s
    s=17/tanx;s=3/tany
    17/tanx=3/tany
    3tanx=17tany
    tanx=17tany/3
    tanA=tan(x+y)
    22/7=tanx+tany/1-tanxtany
    22(1-tanxtany)=7(tanx+tany)
    22-22tanxtany=7tanx+7tany
    Since tanx =17tany/3,
    22-22(17tany/3)tany=7(17tany/3)+ 7tany
    22-(374tan²y/3)=(119tany/3)+7tany
    66-374tan²y=119tany+21tany
    -374tan²y-140tany+66=0
    374tan²y+140tany-66=0
    Using quadratic formula :
    tany =3/11 ; -11/17
    Using 3/11=tany,y=15.2551187...deg
    tanx=17tany/3
    tanx=17(3/11)/3
    tanx=17/11
    x=57.09475708
    s=17/tanx
    s=17/(17/11) ; s= 11
    Area = ½bh
    = ½(20)(11)
    =10(11)
    =110sq. units.
    hehhe answer by: Libres Emmanuel
    From:PUP Taguig Campus

    10:37 PM

    By Anonymous Anonymous, at 10:47 PM  

  • just click the link below
    for my answer
    http://img60.imageshack.us/my.php?image=week2500210uw2.jpg

    By Anonymous Anonymous, at 7:46 AM  

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