標題:
F Maths Problems
發問:
1) (3(10^2a))/(6(10^a)=?2) The base radius and slant height of a cone are increased by 10% and decreased by 15% respectively. Find the percentage change in the curved surface area of the cone.3) It is given that the sides of a triangle are 5cm, 9cm and x cm. Which of the following is possible value of... 顯示更多 1) (3(10^2a))/(6(10^a)=? 2) The base radius and slant height of a cone are increased by 10% and decreased by 15% respectively. Find the percentage change in the curved surface area of the cone. 3) It is given that the sides of a triangle are 5cm, 9cm and x cm. Which of the following is possible value of x? 4)In the figure,L1 and L2 are lines passing through the origin with slopes 2 and 3/5 respectively. The angle between the two line is? Fiugre:http://postimg.org/image/6hhqm9igp/ 5) Mike with eye-level of 1.6m is standing on a tower with a height of 60m. He is starring on the roof of a building which is at ground level.If the roof is 15m high and the horizontal distance between Mike and the building is 100m, find the angle of depression of the roof from Mike. Figure:http://postimg.org/image/lcxfuy7l3/ 6)The figure shows a tetrahedron . BCD is a horizontal plane while AB stands Vertically. M is the mid-point of CD. N is a point CD such that AN is perpendicular with CD. If the length of AC is different from that of AD, which of the followings of CANNOT be the angle between the planes ACD adn BCD? Figure:http://postimg.org/image/st0xg593d/ Need Steps, plz!
1. (3 × 102?) /(6 × 10?) = (3/6) × 102??? = 10?/2 ==== 2. A : the curved surface area r : base radius h : the slant height A = 2 π r h Originally, Ao = 2 π ro ho When r = ro(1 + 10%) and h = ho(1 - 15%) : A = 2 π ro(1 + 10%) ho(1 - 15%) = 0.935Ao % change in the curved surface area = (0.935 - 1) × 100% = -6.5% ==== 3. The length of the longest side of a triangle must be shorter than the sum of lengthsof the two other sides. Case 1 : When x cm is the length of the longest side : x ≥ 9 and x < 5 + 9 x ≥ 9 and x < 14 9 ≤ x < 14 Case 2 : When x cm is not the length of the longest side : x ≤ 9 and x + 5 > 9 x ≤ 9 and x > 4 4 < x ≤ 9 9 ≤ x < 14 or 4 < x ≤ 9 Range of x : 4 < x < 14 (Choose the answer according to the above range of x.) ==== 4. tanθ = [2 - (3/5)] / [1 + 2(3/5)] = (7/5) / (11/5) = 7/11 Angle between the two lines, θ = 32.47° ==== 5. tanθ = (1.6 + 60 - 15) / 100 = 0.466 Angle of depression, θ = 25.0° ==== 6. What are the options to choose ? The given information seems to be insufficient.
其他解答:
1)(3(10^2a))/(6(10^a)) =(3/6)(10^2a / 10^a) =(1/2)(10^(2a-a)) =10^a / 2 0r you can say 5* 10^(a-1)
F Maths Problems
發問:
1) (3(10^2a))/(6(10^a)=?2) The base radius and slant height of a cone are increased by 10% and decreased by 15% respectively. Find the percentage change in the curved surface area of the cone.3) It is given that the sides of a triangle are 5cm, 9cm and x cm. Which of the following is possible value of... 顯示更多 1) (3(10^2a))/(6(10^a)=? 2) The base radius and slant height of a cone are increased by 10% and decreased by 15% respectively. Find the percentage change in the curved surface area of the cone. 3) It is given that the sides of a triangle are 5cm, 9cm and x cm. Which of the following is possible value of x? 4)In the figure,L1 and L2 are lines passing through the origin with slopes 2 and 3/5 respectively. The angle between the two line is? Fiugre:http://postimg.org/image/6hhqm9igp/ 5) Mike with eye-level of 1.6m is standing on a tower with a height of 60m. He is starring on the roof of a building which is at ground level.If the roof is 15m high and the horizontal distance between Mike and the building is 100m, find the angle of depression of the roof from Mike. Figure:http://postimg.org/image/lcxfuy7l3/ 6)The figure shows a tetrahedron . BCD is a horizontal plane while AB stands Vertically. M is the mid-point of CD. N is a point CD such that AN is perpendicular with CD. If the length of AC is different from that of AD, which of the followings of CANNOT be the angle between the planes ACD adn BCD? Figure:http://postimg.org/image/st0xg593d/ Need Steps, plz!
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最佳解答:1. (3 × 102?) /(6 × 10?) = (3/6) × 102??? = 10?/2 ==== 2. A : the curved surface area r : base radius h : the slant height A = 2 π r h Originally, Ao = 2 π ro ho When r = ro(1 + 10%) and h = ho(1 - 15%) : A = 2 π ro(1 + 10%) ho(1 - 15%) = 0.935Ao % change in the curved surface area = (0.935 - 1) × 100% = -6.5% ==== 3. The length of the longest side of a triangle must be shorter than the sum of lengthsof the two other sides. Case 1 : When x cm is the length of the longest side : x ≥ 9 and x < 5 + 9 x ≥ 9 and x < 14 9 ≤ x < 14 Case 2 : When x cm is not the length of the longest side : x ≤ 9 and x + 5 > 9 x ≤ 9 and x > 4 4 < x ≤ 9 9 ≤ x < 14 or 4 < x ≤ 9 Range of x : 4 < x < 14 (Choose the answer according to the above range of x.) ==== 4. tanθ = [2 - (3/5)] / [1 + 2(3/5)] = (7/5) / (11/5) = 7/11 Angle between the two lines, θ = 32.47° ==== 5. tanθ = (1.6 + 60 - 15) / 100 = 0.466 Angle of depression, θ = 25.0° ==== 6. What are the options to choose ? The given information seems to be insufficient.
其他解答:
1)(3(10^2a))/(6(10^a)) =(3/6)(10^2a / 10^a) =(1/2)(10^(2a-a)) =10^a / 2 0r you can say 5* 10^(a-1)
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