F.4 Maths:Quadratic equation (b)(ii) AND(iii) AND (c)?
回答 (1)
2017-11-02 3:03 pm
B(ii)
AD=BD --->angle ABD=angle BAC=36
angle ABC=(180-36)/2=72 ---> angle CBD=72-36=36
triangle ABC is similar to triangle BCD (AA)
(iii)
AB/BC=BC/CD
(C)
(i)AB/2=2/x --->AB=4/x
(ii)
4/x=x+2
x^2+2x-4=0
(iii)
x=-1+√5
AD=BD --->angle ABD=angle BAC=36
angle ABC=(180-36)/2=72 ---> angle CBD=72-36=36
triangle ABC is similar to triangle BCD (AA)
(iii)
AB/BC=BC/CD
(C)
(i)AB/2=2/x --->AB=4/x
(ii)
4/x=x+2
x^2+2x-4=0
(iii)
x=-1+√5
收錄日期: 2021-04-24 00:46:46
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20171102031045AA61Fnf