數學面積題,急！！！?
回答 (3)
2016-02-07 5:00 am
The diameter of the circle = 10cm
therefore, BD or AC = 10cm
angle BDC (angle DBC) = 45degree
angle C = 90 degree
Use trigonometry sine theta = opposite/hypotenuse
sin45 = BC/10
BC=10xsin45
BC= 7.071067812
or
Because sin45 = √2/2
Therefore, x/10 = √2/2
10√2=2x
x=7.071067812
Area of ABCD = (7.071067812)^2 = 50cm^2
therefore, BD or AC = 10cm
angle BDC (angle DBC) = 45degree
angle C = 90 degree
Use trigonometry sine theta = opposite/hypotenuse
sin45 = BC/10
BC=10xsin45
BC= 7.071067812
or
Because sin45 = √2/2
Therefore, x/10 = √2/2
10√2=2x
x=7.071067812
Area of ABCD = (7.071067812)^2 = 50cm^2
2016-02-07 5:02 am
圓的半徑 = 5cm
正方形ABCD邊長的一半 = 5*(1/√2) cm
所以正方形ABCD邊長 = 10*(1/√2) cm
所以正方形ABCD面積 = (10*(1/√2))^2 = 50 (cm)^2
正方形ABCD邊長的一半 = 5*(1/√2) cm
所以正方形ABCD邊長 = 10*(1/√2) cm
所以正方形ABCD面積 = (10*(1/√2))^2 = 50 (cm)^2
2016-02-07 5:38 am
AC=BD=10 cm
AB=BC=CD=AD
AB^2+BC^2=AC^2
2AB^2=100
AB^2=50
正方形ABCD面積=50
AB=BC=CD=AD
AB^2+BC^2=AC^2
2AB^2=100
AB^2=50
正方形ABCD面積=50
收錄日期: 2021-04-18 14:23:22
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160206202308AAzFEWG