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How to calculate sin15 ° times sin30 ° times sin75 Explain how to make 15 and 75
sin30=1/2
The original formula = 1 / 2 * sin (15) * sin (π / 2-15) = 1 / 2 * sin (15) * cos (15)
=1/4*(2*sin(15)cos(15))=1/4*sin(30)=1/8
How to calculate sin15 times sin30 times cos75
=sin15°×cos(90°-15°)×sin30°
=Sin15 °× sin15 °× sin30 ° [because cos (90-15 °) = sin15 °]
=Square of sin15 ° x sin30 °
=(1-cos30 °) / 2 × sin30 ° [because Cos2 α = 1-2 (the square of sin α)
So (the square of sin α) = (1-cos2 α) / 2]
=(1-radical 3 / 2) / 2 × 1 / 2
=(2-radical three) / 8
It's tiring to play mathematical symbols in Baidu
I don't know if you can read it
Cut a cube with an edge length of 8 cm into two cuboids. What is the total surface area of the two cuboids?
8 × 8 × 6 + 8 × 8 × 2, = 64 × (6 + 2), = 512 (square centimeter); answer: the sum of the surface area of the two cuboids is 512 square centimeter
A cuboid is 9 cm long and 8 cm wide. The total length of its edges is 88 cm. The surface area of the cuboid is () and its volume is ()
A cuboid is 9 cm long and 8 cm wide. The total length of its edges is 88 cm. The cuboid has a surface area of (314 square cm) and a volume of (360 cubic cm)
Sum of edge length = 4 (9 + 8 + width) = 88cm
Width = 5 cm
The surface area of a cuboid is 208 square centimeters, and the bottom surface is 8 centimeters long and 6 centimeters wide?
8 * 6 * 2 = 96 (square centimeter)
208-96 = 112 (cm2)
(8 + 6) * 2 = 28 (CM)
112 / 28 = 4 (CM)
A: the height of a cuboid is 4cm
The sum of the edges of a cuboid is 76 cm long. The cuboid is 8 cm long, 6 cm wide, and 10 cm high______ Cm, the surface area of the cuboid is______ Square centimeter, the volume is______ Cubic centimeter
76 △ 4-8-6 = 19-8-6 = 5 (CM) surface area: (6 × 8 + 8 × 5 + 5 × 6) × 2 = (48 + 40 + 30) × 2 = 118 × 2 = 336 (square cm) volume: 5 × 8 × 6 = 240 (cubic cm); answer: the surface area of this cuboid is 336 square cm, and the volume is 240 cubic cm. So the answer is: 5; 336; 240
The surface area of a cuboid is 336 square centimeters, and its length and width are 8 centimeters
Set the height to X
（8*8+8x+8x）*2=336
x=6.5
Cuboid volume = 8 * 8 * 6.5 = 416 CC
A cuboid is made up of three cube blocks with 8 cm long edges. What is the surface area of the cuboid? What is the sum of the edges? What is the volume?
Length 3x8 = 24 width 8 height 8
Surface area (24x8 + 8x8 + 8x24) x2 = 896cm2
The sum of ridge length is (8 + 8 + 24) X4 = 160cm
Volume 24x8 = 1536 CC
Cut a cube with an edge length of 8 cm into two cuboids. What's the total surface area of the two cuboids? What's the surface area of a cuboid made of two cube wood blocks with an edge length of 5 cm? Paint the four top pillars of a building hall. The cross section of each pillar is 0.5 square. The height of each pillar is 5 meters. The paint is 4 yuan per square meter, How much is the total cost? A classroom is 8m long and 6m wide. It needs to paint the walls and ceiling of the classroom. If the area of the doors and windows is 22 square meters, and the average paint is 0.25 kg per square meter, how much is the total income of 25 yuan per kg of paint
1. The surface area of each cube is: 8 × 8 × 6 = 384 (square centimeter). The surface area of two cubes is: 384 × 2 = 768 (square centimeter). The sum of the surface areas of the two cubes is: 768 + 8 × 8 × 2 = 896 (square centimeter) 2. The surface area of two cubes is: 5 × 5 × 6 × 2 = 300 (square centimeter)
The three cuboids are all 8 cm long and form a cuboid. The cuboid has a surface area of () square cm and a volume of () cubic cm
The three cuboids are 8 cm in length, which form a cuboid. The cuboid has a surface area of (896) square cm and a volume of (1536) cubic cm
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