41) Total surface area of a hemisphere is
A) 2π r2
B) 3π r2
C) 4π r2
D) π r2
View Answer
B) 3π r2
Explanation:Total surface area = 3π r2
42) If the radius of base of a cylinder is doubled and the height remains unchanged, then its curved surface area is
A) double
B) three times
C) four times
D) no change
View Answer
A) double
Explanation:r = 2r, h = h
Curved surface area = 2πrh
= 2π (2r) h
= 2(2πrh)
43) If a right-angled triangle is revolved about its hypotenuse, then it will form a
A) Sphere
B) Cube
C) Cone
D) Cylinder
View Answer
C) Cone
Explanation:Cone
44) tan 85° tan 65° tan 45° tan 25° tan 5° =
A) 1
B) 0
C) -1
D) None of these
View Answer
A) 1
Explanation:tan 85°.tan 65°.tan 45°.tan (90 – 65°).tan (90-85°)
= tan 85°.tan 65°.l.cot 65°.cot 85° = 1
45) If sin 18° = cos x, then x =?
A) 73°
B) 37°
C) 72°
D) 84°
View Answer
C) 72°
Explanation:sin 18° = cos x
sin 18° = sin (90 -x)
90 -x = 18° => 90 – 18 = x = 72°
46) =
A) sec θ
B) tan θ
C) sin θ
D) cot θ
View Answer
B) tan θ
Explanation:
= tanθ
47) If ∠A = 60°, then 3sin3 A – 4sinA =
View Answer
A)
Explanation:3(sin 60°)
3 – 4sin 60° =
=
=
48) If a cos θ + b sin θ = p; a sin θ- b cos θ = q, then which of the following conditions is true?
A) a2 + b2 = p2 + q2
B) a2 + b2 = P2 -q2
C) a2 -b2 = p2 + q2
D) a2 -b2 =p2 -q2
View Answer
A) a2 + b2 = p2 + q2
Explanation:a2 cos2θ + b2 sin2θ + 2ab sinθ cosθ = p2
a2 sin2 θ + b2 cos2 θ – 2ab sinθ cosθ = q2
a2 + b2 = p2 + q2
49) If tan α = 1/2., tan β = 1/3, then (α+β)=
A) 30°
B) 60°
C) 45°
D) 0°
View Answer
C) 45°
Explanation:tanα = 1/2., tan β = 1/3,
Tan (α+β) =
=
= 1
∴ (α+β) = 45°
50) If the angle of elevation of the sun is 60°, then the ratio of the height of a tree with its shadow is
A) 1 : 1
B) 1 : √3
C) √3 : 1
D) None of these
View Answer
C) √3 : 1
Explanation:tan 60°= h/x
⇒ √3/1 = h/x ⇒ h : x = √3 : 1
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