Simplification: sin30 ° sin60 − tan60 °=______ ．

The original formula = 1232-3 = 3 − 333 = - 233

120 degrees?

√3/2

How to calculate the trigonometric function value of 18 degrees?

SIN3 α = sin (α + 2 α) = sin α Cos2 α + cos α sin2 α = sin α (1-2sin2 α) + 2Sin α (1-sin2 α) = 3sin α - 4sin3 α (triple angle formula) ∫ sin54 ° = cos36 °; 3sin18 ° - 4sin318 ° = 1-2sin218 °; 4sin318 ° - 2sin218 ° - 3sin18 ° + 1 = 0

List of high school obtuse trigonometric function knowledge points & obtuse trigonometric function derivation process
(derived from trigonometric function of acute angle)

For example, if the angle B is an obtuse angle, then (b-90) is an acute angle, then SINB = sin (b-90 + 90). In this case, (b-90) is regarded as a whole, then we know from the trigonometric function of the acute angle (assuming that the acute angle is a): sin (a + 90) = cos (a). From this, we can get SINB = sin (b-90 + 90) = cos (b-90)

For a cuboid, the bottom area is 42cm, the perimeter of the bottom surface is 26cm, and the height is 5cm

42×2+26×5
=84+130
=214
A: the surface area of this cuboid is 214 square centimeters

The surface area of the cuboid is 78 square meters, the bottom area is 15 square meters, and the perimeter of the bottom surface is 16 meters

This problem should be to find the volume of this cuboid, right?
According to the bottom area and perimeter of the cuboid, the cuboid is 5m long and 3M wide
The sum of the area around the cuboid is 78-15 × 2 = 48 square meters
So the height of the cuboid: 48 △ 16 = 3M
Cuboid volume: 15 × 3 = 45 cubic meters or 5 × 3 × 3 = 45 cubic meters

The surface area of a cuboid is 78 square centimeters, the bottom area is 15 square centimeters, and the perimeter of the bottom surface is 16 centimeters

The perimeter of the bottom surface is 16 cm
16 △ 2 = 8 cm (L + W)
78 △ 2-15 = 24 square centimeters (L × H + W × h)
24 △ 8 = 3 (high)
Volume = 15 × 3 = 45 CC

The surface area of a cuboid is 78 square centimeter, the bottom area is 15 square centimeter, and the perimeter of the bottom surface is 16 square

Is the perimeter of the bottom 16 cm?
Bottom perimeter × height = side area
Side area + bottom area × 2 = surface area
Therefore, height = (surface area - bottom area × 2) × perimeter of bottom surface
=(78-15×2)÷16
=3 (CM)
Volume = bottom area × height = 15 × 3 = 45 (cm3)

The surface area of a cuboid is 70 square centimeters, the bottom area is 9.8 square centimeters, and the perimeter of the bottom surface is 18 centimeters
There are several more questions:
The bottom of a cuboid is a square. Unfold its side to get a square with a circumference of 80 cm
A cube container with 5 decimeters edge length is just full after putting a cube iron block with 2 decimeters edge length. How many decimeters is the water depth in the original container?
Is the second question 32000cm or 500cm? Some people say that which of the two answers is right?
Three questions should be listed, not equations, the best way to solve the problem.

1. 70-9.8-9.8 = 50.4 (area of four faces) 50.4/18 = 2.8 (height) 9.8 * 2.8 = 27.44 cubic centimeter 2.80/4 = 20 (height) 20 / 4 = 5 (length = width) 20 * 5 * 5 = 500 cubic centimeter 3.5 * 5 * 5 = 125 cubic decimeter 2 * 2 * 2 = 8 cubic decimeter 125-8 = 117 cubic decimeter (volume of water) 117 / 5 / 5 = 4.68 decimeter (volume of water)

The sum of all the edges of a cuboid is 120 decimeters. The ground of the cuboid is a square, and its perimeter is 44 decimeters. The surface area of the cuboid and the

Length + width + height = 120 / 4 = 30 decimeters
If the bottom is square, length = width = 44 / 4 = 11 decimeters
Height = 30-11 * 2 = 8 decimeters
Surface area: 2 * (11 * 11 + 11 * 8 + 11 * 8) = 594 square decimeters
Volume: 11 * 11 * 8 = 968 cubic decimeter

Simplification: sin30 ° sin60 − tan60 °=______ ．