Question
In a triangle ABC, D, E and F are the mid-points of the
sides BD, CA and AB, respectively. BE and DF intersect at X. DE and CF intersect at Y. Find XY = ?Solution
In ΔABC, F is the midpoint of AB and E is the midpoint of AC. ∴ By Midpoint Theorem, EF ∥ BC ∴ EF ∥ BD ----(1) ⇒ EF = BC/2 ----(2) Since D is the midpoint of BC, ⇒ EF = BD ----(3) From equation 1 and 3, ⇒ BDEF is a Parallelogram. BE and DF intersect at X. Similarly, DCEF is a Parallelogram. DE and CF intersect at Y. ∵ X and Y are the midpoints of sides DF and DE, respectively. In ΔDEF, X is the midpoint of DF and Y is the midpoint of DE. ∴ By Midpoint Theorem, ⇒ XY = EF/2 ----(4) From equation 3 and 4 ⇒ XY = BC/4
The average number of toffees distributed among five boys is 8. If each boy received 1 toffee more than the boy before him, then find the highest number...
The average rainfall in a city for the first 7 days of a month is 12 mm per day. To have an average of 20 mm per day over 14 days, what should be the av...
Average of 10 observations calculated by a student was 60 but when he again went through his observations he realised that he took value of three observ...
The average weight of 9 students in a seminar is 42 kg. If the weight of 4 facilitators is also included, then the new average weight of each person (fa...
Average run scored by a batsman in first ‘x’ matches is 43. In next 14 matches he scored runs with an average of 63 so that his overa...
- KL Rahul has an average score of 75 runs in 130 innings. The highest runs scored by him in an innings exceed his lowest score by 170 runs. If the runs scor...
Class 'P' has a total of 160 students. The ratio of girls to boys in this class is 2:6. The average number of boys in classes 'P' and 'Q' is 180, and th...
The average weight of a group of five persons, A, B, C, D, and E is 60 kg. If another person K joins the group then the average weight of the group is d...
The ages of 5 children are 6, 8, 10, 12 and 14 years. Find their average age.
In an examination, the average marks obtained by the students is 75. After correcting the quantitative mistakes, the average of 100 students is reduced ...