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If Sin2 30⁰ + Cos4 45⁰ = X then the value of 1/X + 1/x2= ?
Sin2 30⁰ + Cos4 45⁰ = X
⇒ 1/4 + 1/4 = X
⇒ 2/4 = X = ½
So, 2 + 4 = 6
If Sin θ + Cos θ = 11/9 then find Sin 2θ = ?
Given,
(Sin θ + Cos θ)2 = (11/9)2
⇒ 1 + 2 Sin θ Cos θ = 121/81
⇒ 2 Sin θ Cos θ = 121/81 – 1
⇒ 2 Sin θ Cos θ = 40/81 = Sin 2θ
If (a + b) : (b + c) : (c + a) ∷ 5 : 6 : 8 and a + b + C = 38 then a + c =?
2 (a + b + C) = 38 K
(a + b + C) = 19K
38 = 19K
K = 2
So, the correct answer a + c = 26
In a triangle ABC, ∠A = 120° AB = 8 cm and AC = 12 find BC = ?
Cos 120° = (82 + 122 – X2)/(2 × 8 × 12) = (64 + 144 - X2)/96
⇒ -1 = (64 + 144 - X2)/96
⇒ -96 = 208 - X2
⇒ X2 = 304
⇒ X = 17.4
In triangle ABC, ∠B = 150° and ∠C = 100°, AD is angle bisector AE is a perpendicular to BC. Find the angle ∠EAD.
∠EAD = ½ |∠B - ∠C| = ½ |150 - 100| = ½ × 50 = 25
If a person traveling in boat where speed of the boat and stream are 20km/h and 30km/h respectively. How much time will he take to reach a point 600 km away if he travels first hour downstream and next hour upstream in reverse direction and so on?
Speed of the boat = 20 km/h and speed of the river = 30km/h
∴ Speed of the boat in downstream = 20 + 30 = 50 km/h
And speed of the boat in upstream = 30 – 20 = 10 km/h
Distance covered by boat in first hour = 50 km
Distance covered by boat in next hour = 10 km/h
∴ Distance covered by boat in 2 hour = 50 – 10 = 40 km
∴ Distance covered by boat in 10 hour = 200 km
Remaining distance = 600 – 200 = 400 km
And remaining time = (400 km) /(50 km/h) = 8 hours.
The ratio of milk and water in three samples is 2 ∶ 3, 2 ∶ 5 and 13 ∶ 7. A mixture containing equal quantities of all three samples is made. What will be the ratio of milk and water in the new mixture?
Let ‘x’ quantity of each of three mixtures to be mixed
Quantity of milk in the new mixture = (2/5)x + (2/7)x + (13/20)x = 187x/140
Quantity of water in the new mixture = (3/5)x + (5/7)x + (7/20)x = 233x/140
∴ Required ratio = 187 ∶ 233
In ΔABC, ∠A = 50°. The internal bisector of ∠B and ∠C meet at point G, inside the triangle while external bisector of ∠B and ∠C meet at point Y, outside the triangle. What is the sum of ∠BGC and ∠BYC?
If the bisectors of ∠B and ∠C meet at point I inside the triangle, then
∠BGC = 90° + ∠A/2
∠BIC = 90° + 50/2 = 90° + 25° = 115°
If exterior bisectors of ∠B and ∠C meet at point Y outside of the triangle, then
∠BOC = 90° – ∠A/2
∠BOC = 90° – 50°/2 = 65°
Sum of ∠BGC to ∠BYC = 115° + 65° = 180°
The cost of fencing small square ground is Rs. 15000. The cost of fencing per m is Rs. 20. Find the cost of fencing of large square ground having side is 10% more than the side of small ground.
Cost of fencing small square ground = 15000
Perimeter of small ground = 18000/20 = 900 m
Side of small square ground = 900/4 = 225 m
Side of large square ground = (225 + 225) × 10/100 = 450 + 1/10 m = 450.1
Perimeter of large square ground = 450.1 × 4 = 1800 m
Cost of fencing of large square ground = 1800 × 20 = Rs. 36000
Akash and Bapan are standing on the same side of a wall and observe that the angles of elevation to the top of the wall are 45° and 60° respectively. If the height of the wall is 100 m, the distance between Aakash and Bapan is: (Use √3 = 1.73 and √2 = 1.41)
Height of the wall PQ = 100m
In ΔPQB
tan60° = PQ/BQ
√3 = 100/BQ
BQ = 100/√3 m
In ΔPQA
Tan 45° = PQ/AQ
1 = 100/AQ
AQ = 100m
AQ = AB + BQ
100 = AB + 100/√3
AB = 100 – 100/√3 = 100 – (1 - 1.73)
AB = 50 – 28.83
AB = 21.17 M
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