The average number of ABCD is 13.5, the average number of ABC is 12, the average number of BCD is 15, and the average number of CDA is 14?

13.5*4=54
12*3=36
15*3=45
14*3=42
54-36=8
54-45=9
54-42=12
54-8-9-12=25
A=9
B=12
C=25
D=8

RELATED INFORMATIONS

1. Given that OA = (- 1,8) ob = (- 4,1) OC = (1,3) in the rectangular coordinate plane, it is proved that △ ABC is an isosceles triangle
2. It is known that, as shown in the figure, OA bisects ∠ BAC, ∠ 1 = ∠ 2
3. In the triangle ABC, ab = AC, O is a point in the triangle ABC, angle OCB = angle OBC, and angle a = 40
4. There is a point O in the equilateral triangle ABC, the angle AOB = 113 ° and the angle BOC = 123 ° to find the degree of the three internal angles of the triangle with AO, Bo and CO as sides
5. As shown in the figure, a, B and C are three points that are not on the same straight line, AA ′‖ BB ′‖ CC ′, and AA ′ = BB ′ = CC ′. Prove: plane ABC ‖ plane a ′ B ′ C ′
6. Plane α‖ plane β, △ ABC is in plane β, three lines AA ', BB', CC 'intersect at a point P, and P is between plane α and plane β, if BC = 5cm, AC = 12cm, ab = 13cm, PA': PA = 3:2, calculate the area of △ a 'B' C '
7. It is known that in the triangle ABC, O is any point in the triangle, and the extension lines of Ao, Bo, CO intersect the opposite sides of D, e, F Verification: AE / EC + AF / FB = AO / OD
8. In △ ABC, Ao, Bo, CO intersect at a point O, ∠ Bao = ∠ Cao, find what triangle △ ABC is There is a three minute time limit
9. If O is the outer center of the acute triangle ABC and Ao, Bo and co intersect with L, m and N respectively, then Ao: Al + Bo: BM + CO: CN=
10. It is known that the triangle ABC is an isosceles triangle with an angle of 3 = 105 ° and the degree of angle 2 and angle 1 On the course evaluation
11. Q: ABC × 4 = CDA, how much is ABCD for
12. Corresponding edges of △ ABC ≌ △ CDA, AB and CD, BC and DA, write other corresponding edges and corresponding angles
13. In △ ABC, it is known that ∠ cab = 60 °, D and E are points on edges AB and AC respectively, and ∠ AED = 60 °, ed + DB = CE, ∠ CDB = 2 ∠ CDE, then ∠ DCB = () A. 15°B. 20°C. 25°D. 30°
14. If the three sides of a right triangle are A-B, a, a + B and both a and B are positive integers, the length of one side of the triangle may be () A. 61B. 71C. 81D. 91
15. It is known that the sum of the two right sides of a right triangle is 5 cm and the hypotenuse is 2 cm, then the area of the right triangle is 2 cm____ .
16. On Pythagorean theorem The teacher asked the students to go home and prepare a 21cm long wooden stick for use in class. In order to prevent the stick from breaking, Xiao Ming wanted to put it into his pencil case. It is known that Xiao Ming's pencil case is a cuboid 20cm long and 8cm wide. Can the stick prepared by Xiao Ming be put into his pencil case? Note: write down the steps
17. As shown in the figure, in △ ABC, a = 30 °, B = 45 °, D is on AB, e is on AC, and AE = EC = De, then ad2: BC2 is equal to______ ．
18. If be: EC = 3:2, AB: EC = 4:1, then AE: AC: BC =?
19. As shown in the figure, in △ ABC, ∠ C = 90 °, a = 30 ° and ab + BC = 12cm, then the length of the hypotenuse AB is______ cm．
20. It is known that on the BC side of the triangle ABC, be = CF is cut to connect AE AF, which means that ab + AC is greater than AE + AF