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Proof: in a right triangle, if a right angle side is equal to half of the hypotenuse, then the acute angle of the right angle is equal to 30 °
It is known that in △ ACB, ∠ ACB = 90 ° and AC = 1
2AB，
It is proved that: ∠ B = 30 °,
Proof: take AB midpoint D, connect CD,
∵ △ ACB is a right triangle, ∵ ACB = 90 °,
∴CD=1
2AB=AD=BD，
∵AC=1
2AB，
∴AC=AD=CD，
The △ ACD is an equilateral triangle,
∴∠A=60°，
∴∠B=180°-90°-60°=30°．
What is the inverse proposition of the proposition "in a right triangle, if an acute angle is equal to 30 degrees, then the right angle to which it is opposite is equal to half of the hypotenuse"?
In a right triangle, if a right angle side is equal to half of the hypotenuse, the angle of the right angle is 30 degrees
Write the inverse proposition of the proposition "in a right triangle, if the length of a right angle side is equal to the general length of the hypotenuse, then the acute angle of the right angle side is equal to 30 °. Is this inverse proposition true? Please prove your judgment
The inverse proposition is: if the acute angle of a right angle side is equal to 30 degrees, then the length of the right angle side is equal to the length of the hypotenuse. This inverse proposition is true. In RT △ ABC, the angle B = 90 degrees, the angle a = 30 degrees, and BD is the center line on the AC side
Given that the two right sides of a right triangle are 3cm and 4cm, the surface area of the geometry obtained by rotating the hypotenuse as the axis for one cycle is calculated I saw the second mock exam in Fengxian District, but the answer is different from my answer. 84pai/5
The radius of the two cones is 12 / 5, which should be well solved (converted into plane calculation) and then substituted into the formula
Cone surface area = side area + bottom area
S = n r squared + n ra
(r bottom radius a bus
The bottom area is not to be calculated
It is known that the two right angles of a right triangle are 3cm and 4cm. Take the straight line where its oblique side is located as the axis, rotate a circle to get a geometry, and calculate the surface area of the geometry 3Q Group B, 4 questions
The height of the triangle, i.e. the radius of the bottom of the rotating cone, r = 3 * 4 / 5 = 2.4cm
Then the surface area formula of the cone can be used to calculate the resultant tension
S=2*pai*r*l
Take the hypotenuse of the isosceles right triangle with the hypotenuse of 6 as the axis, rotate for one cycle, and calculate the surface area of the figure
Let AB be the hypotenuse of the isosceles right triangle ABC, ab = 6,
Take AB as the axis and rotate for one cycle to get two cones,
The bottom radius is 3, the height is 3, and it is expanded into two fans,
S=πrL,r=3,L=3√2,
∴S=π×3×3√2×2
=18π√2.
Given that the lengths of the two right angles of a right triangle are 3cm and 4cm respectively, the surface area of the geometry is obtained by rotating the hypotenuse as the axis for one cycle______ .
As shown in the figure, let AC = 3, BC = 4, where OC intersects AB and O, then OC is the radius of the bottom surface common to the two cones. Let AC = 3, BC = 4, ab = ac2 + BC2 = 32 + 42 = 5, ∵ ab · OC = AC · BC
A right triangle is looped 360 degrees along the oblique side. The right angle side is 3cm long and the other is 4cm long. The surface area of the geometric figure after the ring is calculated
The radius is the hypotenuse g, and the height is the height h of the hypotenuse of the triangle
G=√(3^2+4^2)=5cm
H*G/2=3*4/2
H=12/5cm
The surface area of the geometry is
3.14*5^2*12/5
=188.4cm^2
The circumference of a right triangle is 26cm, the length of two right angles is 8 cm and 5.5cm, and the oblique side is long______ Centimeter
26-8-5.5 = 12.5 (CM);
Answer: the bevel is 12.5 cm long;
So the answer is: 12.5
It is known that the sum of the two right sides of a right triangle is 2. Find the minimum length of the hypotenuse and the length of the two right angles when the length of the oblique side reaches the minimum
Let X be a right triangle,
Then x + y = 2, (x + y) 2 = x2 + Y2 + 2XY = 4,
∴x2+y2=4-2xy，
∵x2+y2≥2xy，
∴4-2xy≥2xy，
In other words, when x = y = 1, the minimum value of the slope length is: XY ≤ 1
4−2xy=
2，
In this case, the two right angles are equal and equal to 1
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