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Challenging maths problem
(1)In the finure,angleABC=90degree and AB=15. it is given that 5BC=4AC.(a) Find AC.(b) If CD=10 and AD=5√21, prove that angleADC=90degree.picture:http://postimg.org/image/z2d0sf161/(2)In the figure,CB perpendicular AB,angleCAB=40 and angleDAB=20.CD=5m a-nd DB=xm.(a) By considering... 顯示更多 (1)In the finure,angleABC=90degree and AB=15. it is given that 5BC=4AC. (a) Find AC. (b) If CD=10 and AD=5√21, prove that angleADC=90degree. picture:http://postimg.org/image/z2d0sf161/ (2)In the figure,CB perpendicular AB,angleCAB=40 and angleDAB=20.CD=5m a-nd DB=xm. (a) By considering triangleABC,express AB in terms of x. (b) Find the value of x.(correct the answer to 4sig.fig.) picture:http://postimg.org/image/n1gmtf24t/ NEED STEP,PLZ!!!
最佳解答:
1.a) 5BC = 4AC BC = (4/5)AC Since angle ABC = 90? AC2 = 152 + BC2 AC2 = 152 + (16/25)AC2 (1 - 16/25)AC2 = 225 (9/25)AC2 = 225 AC2 = 625 AC = 25 b) CD = 10 CD2 = 100 AD = 5√21 AD2 = 25×21 = 525 CD2 = AD2 = 100 + 525 = 625 = AC2 ==> angle ADC = 90? 2013-12-19 18:42:21 補充： x/AB = tan20? x/tan20? = AB AB = x/0.363970234 AB = 2.747x (5+x)/AB = tan40? (5+x)/2.747x = tan40? (5+x)/2.747x = 0.8391 5+x = 2.305x 5 = 2.305x - x = 1.305x x = 5/1.305 = 3.831 checking : (5+x)/2.747x = (5+3.831)/(2.747)(3.831) = 0.8391 = tan40?
其他解答:
還是要去 http://aaashops。com 品質不錯，老婆很喜歡。 唑古僕|||||i want ot ask whyAB=x/0.363970234 and change to 2.747xA9A3995907B431A4
Challenging maths problem
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發問:(1)In the finure,angleABC=90degree and AB=15. it is given that 5BC=4AC.(a) Find AC.(b) If CD=10 and AD=5√21, prove that angleADC=90degree.picture:http://postimg.org/image/z2d0sf161/(2)In the figure,CB perpendicular AB,angleCAB=40 and angleDAB=20.CD=5m a-nd DB=xm.(a) By considering... 顯示更多 (1)In the finure,angleABC=90degree and AB=15. it is given that 5BC=4AC. (a) Find AC. (b) If CD=10 and AD=5√21, prove that angleADC=90degree. picture:http://postimg.org/image/z2d0sf161/ (2)In the figure,CB perpendicular AB,angleCAB=40 and angleDAB=20.CD=5m a-nd DB=xm. (a) By considering triangleABC,express AB in terms of x. (b) Find the value of x.(correct the answer to 4sig.fig.) picture:http://postimg.org/image/n1gmtf24t/ NEED STEP,PLZ!!!
最佳解答:
1.a) 5BC = 4AC BC = (4/5)AC Since angle ABC = 90? AC2 = 152 + BC2 AC2 = 152 + (16/25)AC2 (1 - 16/25)AC2 = 225 (9/25)AC2 = 225 AC2 = 625 AC = 25 b) CD = 10 CD2 = 100 AD = 5√21 AD2 = 25×21 = 525 CD2 = AD2 = 100 + 525 = 625 = AC2 ==> angle ADC = 90? 2013-12-19 18:42:21 補充： x/AB = tan20? x/tan20? = AB AB = x/0.363970234 AB = 2.747x (5+x)/AB = tan40? (5+x)/2.747x = tan40? (5+x)/2.747x = 0.8391 5+x = 2.305x 5 = 2.305x - x = 1.305x x = 5/1.305 = 3.831 checking : (5+x)/2.747x = (5+3.831)/(2.747)(3.831) = 0.8391 = tan40?
其他解答:
還是要去 http://aaashops。com 品質不錯，老婆很喜歡。 唑古僕|||||i want ot ask whyAB=x/0.363970234 and change to 2.747xA9A3995907B431A4
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