I. 1 .× 2 .× 3。 √
Ii. 1. D2
Three. 1. 120 2.B3.75 4.25
Four.
1. Solution: ∫∠2+∠3 = 180.
∴a∥b (the internal angles on the same side are complementary and the two straight lines are parallel)
∵∠3=∠4
∴c∥d (same angle, two parallel straight lines)
∫a∨b
∴∠ 3 =∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠
∵∠3+∠5= 180
∠3=60
∴∠5= 120
3. Use parallel lines with equal internal angles: two mirrors are parallel, so 90-∠2=90-∠3, so ∠2=∠3, then ∠1+∠ 2 = ∠ 3+∠.
One.
1.6a^3
2.70
3.4025x^2
4. obtuse angle
Ii. 1. A
2.C
3.( 1) Number of children enrolled in school (2)200 1
4.A
5.D
6.D
VII .. b
8.D
9.C
Three.
1.x^2
2.5
3.0.9a
4. Water temperature
5.y=40-5x (y-40)/-5
6. 16 (Q-40)/-6
7. 10 liter per ton, 20 liters for 6 seconds.
8. Because the two values are different, a number is negative.
When x is negative, x+y = 4 | x |+y | =-x+y = 7.
X=- 1.5 y=5.5 x-y=-7。
When y is negative, x+y = 4 | x |+y | = x-y = 7.
x=5.5 y=- 1.5 x-y=7
Four.
2.9
3.20
6.C
7.C
P34
1.A
2.C
3. 150
4. Solution: ∠ AMG = ∠ 3
Reason: ∫≈ 1 =∠2,
∴AB∥CD (the inner angles are equal and the two straight lines are parallel).
∵∠3=∠4,
∴CD∥EF (internal dislocation angles are equal and two straight lines are parallel).
∴AB∥EF (two lines parallel to the same line are parallel).
∴∠AMG=∠5 (two straight lines are parallel and have the same included angle).
∠5=∠3,
∴∠AMG=∠3.
5.( 1) Set up a walkman with X yuan and a schoolbag with Y yuan.
X+y=452 x=4y-8 If you substitute 2 into 1, you get 4y-8+y=452, y=92 and x=360.
(2) If you buy it in A, it will cost 452*0.8=36 1.6 yuan.
If you buy it at B, 452-30=422 yuan.
So it's cheaper for him to buy it in the supermarket.
1.3
2.C
3.B
4. Xiaohong means that the same angle is equal and two straight lines are parallel.
Xiaohua's reason: the internal angles are equal and the two straight lines are parallel.
Another set of parallel lines: AB//CE Reason: ∠ABC=∠ECD →AB//CE (same angle, two parallel lines)
mathematical problem
That makes sense. There are 99 items in Sanduo, and one item refers to three items (also refers to three scholars), all of which are singular.