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Each blank: 1 Mark
$\angle AOD$ = 40+20+30 = 90${}^{\circ }$ = A right angle
$\angle COA$ = 20+30 = 50${}^{\circ }$ = An acute angle
$\angle AOE$ = 40+40+20+30 = 130${}^{\circ }$ = An obtuse angle
$\angle EOC$ = 40+40 = 80${}^{\circ }$ = An acute angle

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Fractions: 1 Mark each
We may observe that in one complete clockwise revolution, the hour hand will rotate through${360}^{\circ }$
a) We have to find out the fraction of a clockwiserevolution that an hour hand turns through when it rotates from 3 to 6.
Now, when the hour hand rotates from 3 to 6 it will rotate through 1 right angle.
$\therefore$ The fraction of revolution =$\frac{{90}^{\circ }}{{360}^{\circ }}$$=$$\frac{1}{4}$ revolution
b) Here the hour hand rotates from 6 to 12, which is to right angles.
$\therefore$ The fraction of revolution =$\frac{{180}^{\circ }}{{360}^{\circ }}$$=$$\frac{1}{2}$ revolution

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Matching: 1 Mark
a. Perpendicular bisector divides the line segment into two equal parts making a right angle. So, figure (ii) shows the perpendicular bisector.
b. In figure (ii) and (iii), the line segments are divided into two equal parts. So, they show bisectors.
c. In figure (iii), the line segment is divided into two equal parts only. So, it shows theonly bisector.
d. In figure (i), the line segment is intersected at ${90}^{\circ }$. So, it shows only a perpendicular.

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Type of triangle: 1 Mark
Properties: 2 Marks
The sides of the triangle are given as 6m, 6m, 8m.
Now two sides of the triangle are equal 6m, 6m.
We know that if a triangle has two sides equal then the triangle is isosceles.
Hence, the given triangle is an isosceles triangle.
Also if two sides of a triangle are equal then their respective angles are also equal.

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Steps: 2 Marks
Answer: 1 Mark
Given that:
The wheel rotates 6 and a half times in one second.
We know that in one revolution there are 4 right angles.
$\therefore$ In 6 revolutions, the number of rightangles = 6$\times$4 = 24
$\therefore$ In half revolution, the number of right angles = $\frac{1}{2}$$\times 4$ = 2
The total number of right angles = 24 + 2 = 26.
The wheel went through 26 right angles.

Answer: Option C. -> Yes, Nonagon 
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C
Yes, it is a polygon, a closed figure bounded by sides. Number of sides is 9. So, it is called Nonagon.

Answer: Option B. -> Straight angle
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B

We can see the angle between north and south direction is 180${}^{\circ }$.

Answer: Option C. -> 2 and 3 
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C
In a parallelogram, opposite sides are equal and diagonals are not equal. All are true except 2 and 3.

Answer: Option C. -> Cylinder 
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C

Just by observing and comparing, we can say that roller resembles the shape of the cylinder.

Answer: Option A. -> 04:30 
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A
At 04:30, the anglebetween the hour hand and minute hand is less than 90^o and at the other given times, the angle between the minuteand the hour hand is more than 90^o.