#Daily Creation Check-in##Grade 7 Mathematics# Seven Mathematics Plane Graphics Understanding: Three Lines, Octagonal Inner Angles and Special Training
Detection of Plane Graphics (Paper 3)
1. Multiple choice questions. (2 marks per question, 20 marks in total)
1. As shown in the figure, point B is a point on the extension line of the side AD of the ADC, ∠C is equal to 40°, ∠BDE is equal to 60°, if you want to make DE∥AC, then the degree of ∠CDB is ( ).
A、70°； B、100°；
C、110°； D、120°。
2. If we know that in △ABC, AB=6 and BC=4, then the length of the edge AC may be which of the following values ( ).
A、11；B、5；C、2；D、1。
3. The sum of the inner angles of the octagon is ( ).
A、180°； B、360°；
C、1080°； D、1440°。
4. If the size of each inner angle of the regular n-sided is 108°, then n should be equal to ( ).
A、5；B、6；C、7；D、8。
5. Place the right-angled vertices of the triangle plate on the two flat lines a and b, as shown in the figure, it is known that ∠1=35°, then the degree of ∠2 is ( )
A、35°； B、45°； C、55°； D、65°。
6. If the two sides of an isosceles triangle are 2 and 5 respectively, then its circumference is ( )
A, 7, B, 9, C, 12, D, 9 or 12.
7. As shown in the figure, AB∥ED, AG bisects ∠BAC, ∠ECF=70°, then the degree of ∠FAG is ( ).
A、155°； B、145°；
C、110°； D、35°。
8. The length of the two sides of the triangle is 2cm and 7cm respectively, and the length of the other side a is an even number, and 2cm<a<8cm, the circumference of this triangle is ( ).
A、13㎝；B、15㎝；
C、17㎝；D、15cm或17㎝。
9. As shown in the figure, OA and OB are two plane mirrors with an angle of 65 degrees, there is a point M on the OB, and a beam of light shot out from the point M is reflected by the point N on the OA, and the reflected ray NS is just parallel to the OB, then the degree of ∠NMB is ( ).
A、65°； B、35°； C、100°； D、130°。
10. As shown in the figure, BE and CF are both angular bisectors of △ABC, and ∠BDC=110°, then ∠A is equal to ( ).
A、50°； B、40°； C、70°； D、35°。
