TS Polycet (Polytechnic) 2015 Previous Question Paper with Answers And Model Papers With Complete Analysis

Q). cos4 A – sin4 A =
A) Sin2 A
B) Cos2 A
C) tan2 A
D) None

View Answer
D) None
Explanation: cos4 A-sin4 A
= (cos2A)2 – (sin2A)2
= (cos2A + sin2A) (cos2A – sin2A)
=1 (cos2A – sin2A)
= cos2A – sin2A

Q). sin 35° cos 35° sin 47° cos 47° cos 90° =
A) 1
B) -1
C) 0
D) sin 45°

View Answer
C) 0
Explanation: sin 35° cos 35° – sin 47°.cos 47°.cos 90°
= sin 35°. cos 35°.sin 47°.cos 47° (0)
=0

Q). tan 5°.tan 30°.4 tan 85° =
A) 4√3
B) 4/√3
C) 1
D) 4

View Answer
B) 4/√3
Explanation: tan 5°.cos 30°.4 tan 85°
= tan 5°.1/√3. 4 tan(90° – 5°)
= tan 5°. 4/√3. Cot 5°
= (tan 5°.cot 5°)4/√3
= 1. 4/√3 =4/√3

Q). If x tanθ + y secθ = p and x secθ + y tanθ = q, then
A) q2 – p2 = x2 + y2
B) q2 + p2 = x2 – y2
C) q2 – p2 = x2 – y2
D) q2 + p2 = x2 + y2

View Answer
C) q2 – p2 = x2 – y2
Explanation: x tanθ + y secθ = p ………..(1)
x secθ + y tanθ = q …………(2)
x2 tan2θ + y2 sec2θ + 2xy tanθ secθ = p2
x2 sec2θ + y2 tan2θ + 2xy tanθ secθ = q2
– – – –
_________________________________
x2 (tan2θ – sec2θ) + y2 (sec2θ – tan2θ) = p2 – q2
– x2+ y2 = p2– q2
x2– y2 = q2– p2

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

View Answer
A) 8/25
Explanation: n(s) = 50
n(A) = {3,6,9,12,15,18; 21,24,27,30,33,36,39, 42, 45, 48) = 16
∴P(A)= n(A)/n(S) = 16/50 = 8/25

Q). If three coins are tossed simultaneously then the probability of getting at least two heads, is
A) 1/4
B) 3/8
C) 1/2
D) None

View Answer
C) 1/2
Explanation: n(S) = 23 =8
n(A) = {HHH, HHT, HTH, THH} = 4
∴P(A)= n(A)/n(S) = 4/8 = 1/2

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