求解國二數學 兩個正方形 周長和76公分 面積和193平方公分 邊長各是多少?
回答 (2)
2018-01-04 10:40 pm
let the sides of the squares be sa, sb.
4 sa + 4 sb = 76.... (1)
sa*sa + sb*sb = 193 ... (2)
from (1)
sa + sb = 19 ... (3)
(sa+sa)^2 = 361 ... (4)
(4) - (2)
sa*sb = (361 - 193)/2 = 84... (5)
from (3) and (5)
sa, sb = 12cm, 7cm
4 sa + 4 sb = 76.... (1)
sa*sa + sb*sb = 193 ... (2)
from (1)
sa + sb = 19 ... (3)
(sa+sa)^2 = 361 ... (4)
(4) - (2)
sa*sb = (361 - 193)/2 = 84... (5)
from (3) and (5)
sa, sb = 12cm, 7cm
2018-01-07 8:37 pm
設周長a和b
a+b=19
a^2+b^2=193
a=19-b代入上式
2b^2-38b+168=0
b^2-19b+84=0
(b-12)(b-7)=0
b=12或7
a=7 或12
a+b=19
a^2+b^2=193
a=19-b代入上式
2b^2-38b+168=0
b^2-19b+84=0
(b-12)(b-7)=0
b=12或7
a=7 或12
收錄日期: 2021-05-03 14:59:48
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20180104143232AASZ3es