24 decimeters is a fraction of 5 meters? Fast!

24 decimeters is a fraction of 5 meters? Fast!

5m = 50m
24÷50=12/25
A: 24 decimeters is 12 / 25 of 5 meters
twelve-twenty-fifths
As shown in the figure, ∠ AOB is an angle placed in the square grid, then the value of cos ∠ AOB is______ .
Suppose that the side length of a square is 12, then Ao = 5, Bo = 5, ab = 2. In △ AOB, according to the cosine theorem, AB2 = AO2 + bo2-2ao · Bo · cos ∠ AOB, ∧ 2 = 5 + 5-2 × 5 × cos ∠ AOB, ∧ cos ∠ AOB = 0.8, so the answer is 0.8
What's 9 decimeters? 9 decimeters = -
9 / 10 meters
9 decimeters = 9 / 10 meters
9 / 10 meters
nine-100ths
Nine tenths
In the square grid, the position of ∠ AOB is shown in the figure, then the value of cos ∠ AOB is______ .
∵ in the right angle △ cod, OD = 1, CD = 2, ∵ OC = 5, ∵ cos ∠ AOB = odoc = 15 = 55
What is 0.8% equal to?
0.8% is equal to 1 / 125
one-125th
1/125
As shown in the figure, in the 3 × 3 square grid, the ∠ 1 and ∠ 2 are marked=______ .
According to Pythagorean theorem, AC = BC = 5, ab = 10. ∵ (5) 2 + (5) 2 = (10) 2, ∵ ACB = 90 degree, ∵ cab = 45 degree. ∵ ad ∥ CF, ad = CF, ∵ quadrilateral ADFC is parallelogram, ∵ AC ∥ DF, ∵ 2 = ∠ DAC (two lines are parallel and the same angle is equal). In RT △ abd, ∵ 1 + ∠ DAB = 90 degree (two acute angles in right triangle are complementary); and ∵ DAB = ∠ DAC+ Therefore, the answer is: 45 °
The value of tan80 ° + tan40 ° - 3tan80 ° tan40 ° is equal to___ .
According to the tangent formula of sum angle, we can get tan120 ° = Tan (80 ° + 40 °) = tan80 ° + tan40 ° 1-tan40 ° × tan80 ° so tan40 ° + tan80 ° = - 3 (1-tan40 ° × tan80 °) so tan80 ° + tan40 ° - 3tan80 ° tan40 ° = - 3, so the answer is: - 3
For a cube dice, 1 and 6, 2 and 5, 3 and 4 are the points on the opposite sides. Now there are 12 square squares with dot like patterns on the paper. As shown in the figure, if you want to make a dice by folding, which six square squares should be cut off? (please use a pen to mark "×" on the square to be cut, without writing the reason)
As shown in the figure
cos80°cos20°+sin100°sin380°=?
sin100=sin(180-100)=sin80
sin380=sin(360+20)=sin20
cos80°cos20°+sin100°sin380°
=cos80cos20+sin80sini20
=cos(80-20)
cos60
=1/2
The formula is cos (a-b) = cosacosb + sinasinb
In a triangle, one side is twice of the other side, and an angle is equal to 30 degrees. Is this triangle a right triangle? Why?
Such as the title
When 30 ° is the opposite angle of the short side, the triangle is a right triangle of 30 °, 60 ° and 90 °; when 30 ° is the angle between the two sides, the triangle is not a right triangle (suppose the short side is x, then the other side is 2x, which can be judged by cosine theorem and sine theorem)
Not necessarily, because 30 degrees may not be the angle of a short pair of sides