q1. in the figure, o is the centre of the circle. the rectangle ABCD is of dimensions 8cmX15cm. find the perimeter of the orange colour region.
***pic: http://pichost.xzmo.com/view.php?p=20070808155953.JPG
q.2 in the figure,CA =CD.
(a). Find the value of x
(b). determine if triangle ACD is a right-angled triangle.
**pic: http://pichost.xzmo.com/view.php?p=20070808160631.JPG
maths questions form 2
2007-08-09 12:18 am
回答 (1)
2007-08-09 12:30 am
✔ 最佳答案
1.AC^2 = AB^2 + BC^2 (Pyth. theorem)
AC^2 = (15cm)^2 + (8cm)^2
AC = 17 cm
So the perimeter of the orange region
= 丌 x 17cm
= 17丌 cm
= 53.4 cm (corr. to 3 sig. fig.)
2a) AC^2 = AB^2 + BC^2 (Pyth. theorem)
x^2 = 7.5^2 + 10^2
x = 12.5
b) CD = AD = 12.5 (given)
CD^2 + AD^2
= 12.5^2 + 12.5^2
= 312.5
AD^2
= 17.5^2
= 306.25
Since CD^2 + AD^2 =/= AD^2, ACD is not a right-angled triangle.
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