1.If two angles are complementary to each other, then each angle will be-
A. acute angle
B. obtuse angle
C. right angle
D. reflex angle
(Sum of two complementary angles are 90 degree. hence, each angle will be less than 90 degree).
2.What is the complementary angle of 72°40’?
A. 108°40’
B. 27°15’
C. 17°20’
D. 13°50’
(60 min= 1 degree
∴40 min=1/60 ×40= 2/3
∴72°40’ – 17°20’= 89°60’
i.e approx. 90°)
3.The measure of an angle is 5 times to its complementary angle. Then the measure of an angle is-
A. 24 degree
B. 40 degree
C. 82 degree
D. 75 degree
(x= 5(90-x)
6x= 450
X=75)
4.If 3∠A=4∠B=∠C, then A:B:C= ?
A. 3:5:6
B. 4:3:12
C. 3:5:7
D. 4:5:7
(By taking L.C.M of 3, 4, 1 we get 12
Then, 3/12, 4/12, 1/12
∴A/4: B/3: C/12
A:B:C= 4:3:12 ans)
5.In a triangle ABC, if ∠A+∠B=125 and ∠A+∠C=113, Find ∠A –
A. 52
B. 63
C. 58
D. 72
(As, ∠C=180-125=55 and ∠B=180-113=67
∴∠A=180-(55+67)=58 ans)
6.The exterior angle of a triangle is 110° and one of its interior angle is 45°. Then its another interior angle is-
A. 65
B. 25
C. 45
D. 105
( Interior angle = 110 – 45= 65 ans)
7.The angles of a triangle are in the ratio of 3:5:7. Then the triangle is-
A. right triangle
B. obtuse triangle
C. acute triangle
D. scalene triangle
(Let measure of triangles are 3x, 5x, 7x.
3x+5x+7x=180
15x=180… x=12
∴ measures are: 36, 60 and 84)
8.AOB is a straight line. If ∠AOC=40 ,∠COD=4x and ∠BOD=3x,Then find ∠COD ?
A. 100
B. 80
C. 120
D. 75
(40+7x=180
7x=140….x=20
COD=4x… 80 ans)
9.AOB is a straight line. If x:y:z = 4:5:6, then y= ?
A. 90
B. 54
C. 66
D. 60
(4x+5x+6x=180
15x=180; x= 12
y= 60 ans)
10.An angle whose measure is more than 180 and less than 360, is known as-
A. acute angle
B. reflex angle
C. right angle
D. obtuse angle
(Reflex angle is in between 180 and 360 degree)
