1) In the first term mathematics examination, the average mark of 200 F.3 students was initially 60. However, 2 students who both had x marks were found cheating during the examination, so they were penalized and their marks were adjusted to 0. If the final average mark was decreased by 1.1%, find the value of x.
2)In triangle ABC, O is a point on AB such that OA=OB=OC.
(a) Find angle ACB
(b)AO produced meets BC at E. Determine whether AE is the perpendicular bisector of BC.
Figure:http://postimg.org/image/g6cv0qxp7/
Need Step, Plz!
F3 Maths Problems
2015-01-05 1:23 am
回答 (2)
2015-01-05 4:16 am
✔ 最佳答案
1.The final average mark is 200*60-2x=12000-2x
So,
((12000-2x)-12000)/12000=-1.1%
12000-2x-12000=-132
-2x=-132
x=66
2.
(a)
OA=OC
Let angle OAC be x, so angle OCA is x
OC=OB
Let angle OBC be y, so angle OCB is y
So,
x+x+y+y=180 (Angle sum of triangle)
x+y=90
Angle ACB=x+y=90
(b)
AO is already met BC
Are there typing error?
2015-01-12 14:18:06 補充：
angle COB=angle CBO
OC=CB (sides opp., equal ∠)
OC=1cm
CB=1cm
OC=OB
OB=1cm
Area of triangle ABC
=(1+1)*√(1^2-0.5^2)
=2*0.75
=1.5cm2
2015-01-05 4:26 am
Sorry, I type the wrong question.
Q2(b) If angle COB=angle CBO and OC=1cm, find the area of triangle ABC.
Q2(b) If angle COB=angle CBO and OC=1cm, find the area of triangle ABC.
收錄日期: 2021-04-15 17:46:54
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