Q). Two towers heights h1 and h2 subtend angles 60° and 30° respectively, at the midpoint of the line joining their feet. Then h1 : h2 =
A) 1:2
B) 3:1
C) 2:1
D) 1:3
View Answer
B) 3:1
Explanation: In ΔABE
tan 60° = h1/EA
√3 = h1/EA ⇒ EA =h1/√3
In ΔCDE
1/√3 = h2/CE ⇒ CE = √3h2
CE = EA
√3h2 = h1/√3 ⇒ h1/h2 = 3 ⇒h1 : h2 = 3 : 1
Q). Two poles are ‘a’ meters apart and the height of one is double of the other. If from the middle point of the line joining their feet an observer finds the angular elevations of their tops to be complementary, then the height of the smaller pole is
A) √2a m
B) a/2√2 m
C) a/√2 m
D) 2a m
View Answer
B) a/2√2 m
Explanation: In ΔABE
tanθ = h/EA
EA =h/tanθ
In ΔCDE
tan (90° – θ) = 2h/CE
cotθ = 2h/CE
CE = 2h/cotθ = 2h tanθ
a/2.a/2 = 2h2 ⇒ h2 = a2/8 ⇒ h = a/2√2
Q). If A and B are supplementary angles, then A + B =
A) 180°
B) 360°
C) 90°
D) 270°
View Answer
A) 180°
Explanation: A and B are supplementary angles then A + B = 180°
Q). The probability of a certain event is
A) 0
B) 1
C) 1/2
D) No existence
View Answer
B) 1
Explanation: The probability of a certain event is 1.
Q). A number is selected from the first 5 natural numbers. What is the probability that it is a multiple of 3?
A) 8/25
B) 10/50
C) 12/25
D) None