9th Grade > Mathematics
LINES AND ANGLES MCQs
Lines And Angles
Total Questions : 74
| Page 2 of 8 pages
Answer: Option C. -> Right angled triangle
:
C
Let the two equal angles be x.
Then the third angle y = 2x
Also we know,
y + 2x = 180°(Sum of the angles of a triangle is 180°)
2x + 2x = 180°
4x = 180°
x = 45°
Hence the two equal angles are 45° each and the other angle is 90°which makes this triangle a right angled triangle.
:
C
Let the two equal angles be x.
Then the third angle y = 2x
Also we know,
y + 2x = 180°(Sum of the angles of a triangle is 180°)
2x + 2x = 180°
4x = 180°
x = 45°
Hence the two equal angles are 45° each and the other angle is 90°which makes this triangle a right angled triangle.
Answer: Option C. -> If the sum of two angles is 90∘, then they are called supplementary angles.
:
C
a)An acute angle measures between 0∘and 90∘, whereas a right angle is exactly equal to 90∘.
b)An angle greater than 90∘but less than 180∘is called an obtuse angle.
c)An angle which is greater than 180∘but less than 360∘is called a reflex angle.
d)If the sum of two angles is 90∘,then they are called complementary angles and if the sum is 180∘,then they are called supplementary angles.
:
C
a)An acute angle measures between 0∘and 90∘, whereas a right angle is exactly equal to 90∘.
b)An angle greater than 90∘but less than 180∘is called an obtuse angle.
c)An angle which is greater than 180∘but less than 360∘is called a reflex angle.
d)If the sum of two angles is 90∘,then they are called complementary angles and if the sum is 180∘,then they are called supplementary angles.
Answer: Option A. -> True
:
A
The sum of two complementary angles is 90∘. Hence, each angle will be less than 90∘
:
A
The sum of two complementary angles is 90∘. Hence, each angle will be less than 90∘
Answer: Option C. -> 24∘ and 156∘
:
C
Since ABis a straight line, ∠AOB=180∘
Therefore, ∠AOC+∠COB=180∘
⇒3x+30∘+2x−60∘=180∘
⇒5x−30∘=180∘
⇒5x=210∘
⇒x=42∘
Therefore,
∠COB=2x−60∘=84∘−60∘=24∘
∠AOC=3x+30∘=126∘+30∘=156∘
:
C
Since ABis a straight line, ∠AOB=180∘
Therefore, ∠AOC+∠COB=180∘
⇒3x+30∘+2x−60∘=180∘
⇒5x−30∘=180∘
⇒5x=210∘
⇒x=42∘
Therefore,
∠COB=2x−60∘=84∘−60∘=24∘
∠AOC=3x+30∘=126∘+30∘=156∘
Answer: Option D. -> 105∘, 75∘, 105∘
:
D
From the figure given in the question, we can observe that
∠3 = 75∘
(Vertically opposite angles)
∠2 +75∘= 180∘
(Angles on a straight line)
⇒ ∠2 = 180∘-75∘= 105∘
∠2 =∠4
(Vertically opposite angles)
⇒∠4 = 105°
:
D
From the figure given in the question, we can observe that
∠3 = 75∘
(Vertically opposite angles)
∠2 +75∘= 180∘
(Angles on a straight line)
⇒ ∠2 = 180∘-75∘= 105∘
∠2 =∠4
(Vertically opposite angles)
⇒∠4 = 105°
Answer: Option B. -> False
:
B
Infinite number of transversals can be drawn for any two given lines.
:
B
Infinite number of transversals can be drawn for any two given lines.
Answer: Option C. -> 190∘
:
C
∠1and 72∘form a linear pair.
So, ∠1 + 72∘ = 180°
⇒ ∠1 = 180°- 72∘
⇒ ∠1 = 108°
Similarly,∠2and 98∘form a linear pair.
So, ∠2+ 98∘ = 180°
⇒ ∠2= 180°- 98∘
⇒ ∠2= 82°
∴∠1+∠2=108°+82°=190°
:
C
∠1and 72∘form a linear pair.
So, ∠1 + 72∘ = 180°
⇒ ∠1 = 180°- 72∘
⇒ ∠1 = 108°
Similarly,∠2and 98∘form a linear pair.
So, ∠2+ 98∘ = 180°
⇒ ∠2= 180°- 98∘
⇒ ∠2= 82°
∴∠1+∠2=108°+82°=190°
Answer: Option C. -> Obtuse Angle
:
C
A clock has a total of 360°.
The angle between any two consecutive numbers on a clock
= 360∘12 = 30∘ [∵ a clock has 12 divisions]
At 8o'clock, the minute hand is at 12 and the hour hand is at8 and there are 4 divisions between 8 and 12.
∴ Theangle between them= 4×30∘
= 120∘
Hence the angleformed at 8 o'clock is an obtuse angle since it is more than 90° and less than 180°.
:
C
A clock has a total of 360°.
The angle between any two consecutive numbers on a clock
= 360∘12 = 30∘ [∵ a clock has 12 divisions]
At 8o'clock, the minute hand is at 12 and the hour hand is at8 and there are 4 divisions between 8 and 12.
∴ Theangle between them= 4×30∘
= 120∘
Hence the angleformed at 8 o'clock is an obtuse angle since it is more than 90° and less than 180°.
Answer: Option B. -> False
:
B
Angles less than 90∘are acute angles.
An obtuse angle is more than 90° but less than 180°
Angles equal to 90∘are right angles.
:
B
Angles less than 90∘are acute angles.
An obtuse angle is more than 90° but less than 180°
Angles equal to 90∘are right angles.
Answer: Option A. -> 1, 2, 7, 8.
:
A
Exterior angles lie outside the parallel lines. The exterior angles are 1, 2, 7, 8.
:
A
Exterior angles lie outside the parallel lines. The exterior angles are 1, 2, 7, 8.
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