Prove that: tan3A tan2A tanA = tan3A−tan2A−tanA
We can write, tan 2A = tan (3A – A) By trigonometry formula, tan(3A-A)=tan3A-tanA/1+tan3AtanA Thus, tan 2A = tan3A-tanA/1+tan3AtanA tan 2A... View Article
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1, 5, 14, 30, 55, 91, ? A. 130 B. 140 C. 150 D. 160
Answer: B.140 1, 5, 14, 30, 55, 91,.. The pattern is: + 4, + 9, + 16, + 25, + 36,…... View Article
A red LED emits light at 0.1Watt uniformly around it. The amplitude of the electric field of the light at a distance of 1m from the diode is: A. 6V/m B. 2.45V/m C. 5.48V/m D. 1.73V/m
Answer: B. 2.45V/m Explanation: Intensity of light, I = P/4πr2 = uav×c uav = 1/2 ∈0E02 \(\begin{array}{l}\frac{P}{4 \pi r^{2}}=\frac{1}{2} \in_{0} E_{0}^{2} \times... View Article
There is no life on moon because of the absence of: A. Water B. Oxygen C. Nitrogen D. Hydrogen
Answer: A. Water
Explain how a square is a parallelogram.
A square has its opposite sides equal and parallel, so, it is a parallelogram.
Write the complete symbol for the atom with the given atomic number (Z) and atomic mass (A). a. Z=17,A=35, b. Z=92,A=233, c. Z=4,A=9
(i) The atom with mass number 35 and atomic number 17 is Chlorine: 35Cl17 (ii) The atom with mass number 233 and... View Article
The percentage of carbon in CO2 is: (A) 0.034% (B) 27.27% (C) 3.4% (D) 28.7%
Answer: (B) 27.27% Mass percentage = (Mass of carbon)/(Molecular mass of compound) x 100 = 12/44 x 100 = 27.27%
In which year the first ozone hole was discovered? A. 1980 B. 1985 C. 1989 D. 1990
Answer: B. 1985
The distance between an octahedral and tetrahedral void in fcc lattice would be: A. a√3 B. a/√3 C. a√3/2 D. a√3/4
Answer: D. a√3/4 The distance between an octahedral and tetrahedral void in fcc lattice would be a√3/4.
What do you mean by electrical resonance? An LC circuit is in a condition of resonance.
The condition when the capacitve reactance becomes equal to inductive reactance is known as electrical resonance. In this condition of... View Article
The function of centrosome is: a. Inhibition of cell division b. Initiates cell division c. To increase protein synthesis d. None of the above
b. Initiates cell division
Denitrification is carried out by which bacteria? A. Pseudomonas B. Nitrobacter C. Nitrosomonas D. Nitrococcus
A. Pseudomonas
The styx number for B2H6 is: A. 2002 B. 2012 C. 2201 D. 2102
Answer: A. 2002 s = number of three-center, B-H-B, bridge bonds = 2 t = number of three-center B-B-B bonds... View Article
The site of cellular respiration in animal cell is: A) ribosome B) mitochondria C) endoplasmic reticulum D) lysosome
Answer: B) mitochondria The site of cellular respiration in animal cell is mitochondria.
A particle is thrown vertically upwards. Its velocity at half of the height is 10m/s, then the maximum height attained by it will be: (g = 10 m/s^2).A) 10mB) 20mC) 15mD) 25m
Answer: A) 10m Solution Let the maximum height be h meter. By the equation of motion formulas, we know; v2... View Article
The sum of squares of first ten natural numbers is:
By the formula of sum of firts n natural numbers, we know, Sn = (1/6) n(n+1)(2n+1) Here n = 10... View Article
Reaction which produces a yellow precipitate is: (A) NaOHaq+HClaq→NaCls+H2O (B) NaOHaq+BaClaq→BaOHs+NaClaq (C) Pb(NO3)2aq+2KIaq→2KNO3aq+PbI2s (D) CuOs+Mgs→Cus+MgOs (E) 4Fe+3O2→2Fe2O3
Answer: (C) Pb(NO3)2 (aq)+2KI(aq) → 2KNO3(aq) + PbI2(s)
In a plane perpendicular to the magnetic meridian, the dip needle will remain: (A) Vertical (B) Horizontal (C) At 45° from horizontal (D) At 60° from vertical
Answer: (A) Vertical In a plane perpendicular to the magnetic meridian, the dip needle will remain vertical.
A bivalent of Meiosis I consists of A. Four chromatids and two centromeres B. Two chromatids and one centromere C. Two chromatids and two centromere D. Four chromatids and four centromere
Answer: A. Four chromatids and two centromeres
If sinx + siny + sinz = 3. Find the value of cosx + cosy+ cosz.
Given, sinx+siny+sinz=3 as we know, sin 90° = 1 So, sin x = sin y = sinz = 1 (that... View Article
