In the triangle ABC, angle a = 50 degrees. If point 0 is the outer center of the triangle ABC, how many degrees is the angle BOC equal to? Why?

In the triangle ABC, angle a = 50 degrees. If point 0 is the outer center of the triangle ABC, how many degrees is the angle BOC equal to? Why?

The circle angle of the same arc is 1 / 2 of the center angle

Students play pitching game, the red and yellow two colors of the ball into the small basket 5 meters away, into a yellow ball 5 points, a red ball 7 points, Xiao Wang a total of 58 points, ask him to throw how many red balls?

Let the red ball be x and the yellow ball be y (XY is an integer, which is the key to solve the problem!), then 5Y + 7x = 58. Generally speaking, there are infinitely many solutions to this equation, but in this problem, X and y are the number of yellow and red balls (only integers), and the score is 58 points. The value of 58 is not too large, so you can take the integers 1, 2, 3 and 4, and then calculate the value of Y (or x), x. Y is an integer, which is the answer. The solution is x = 6, y = 4

If point a (3,5, - 7) and point B (- 2,4,3) are known, then the projective length of line AB on the coordinate plane YOZ is?
Does the line AB cross the plane YOZ? If so, how can we find the projection?

A. The projections of B on the YOZ plane are: a '(0,5, - 7), B' (0,4,3)
Therefore, the projective length is | a'B '| = radical (1 + 100) = radical (101)
(it is not necessary to consider whether the line AB crosses the plane YOZ)

Judgment: in △ ABC, if ∠ C = 90 °, then AB & # 178; + BC & # 178; = AC & # 178; right?

In △ ABC, if ∠ C = 90 °, then AB & # 178; + BC & # 178; = AC & # 178;
Error; ∠ C faces AB, so it's AB & # 178; = BC & # 178; + AC & # 178
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Factorization of a ^ n + 2 + A ^ n + 1b-6a ^ NB ^ 2

Point a and B are the left and right ends of the major axis of the ellipse x ^ 2 / 36 + y ^ 2 / 20 = 1, respectively. Point F is the right focus of the ellipse
Points a and B are the left and right ends of the major axis of the ellipse x ^ 2 / 36 + y ^ 2 / 20 = 1, respectively. Point F is the right focus of the ellipse. Point P is on the ellipse and above the X axis, and PA is perpendicular to PF
(1) (2) let m be the point on the major axis ab of the ellipse, and the distance from m to the straight line AP is equal to | MB |, then find the minimum distance d from the point on the ellipse to the point M.

The problem is not complete

It is known that in the triangle ABC, the angle a is equal to 90 degrees, ab = AC, D is the midpoint of BC. E. f are the points on AB and AC respectively, and be = AF. it is proved that the triangle DEF is a triangle
Waist right triangle

Certification:
Connect ad
∵∠ a = 90 °, ab = AC, D is the midpoint of BC
∴AD⊥BC,∠CAD=∠BAD=∠B=45°
∴AD=BD,
∵BE=AF
∴△DBE≌⊿DAF
∴ED=DF,∠ADF=∠BDE,
∴∠EDF=∠ADB=90º
The triangle DEF is an isosceles right triangle
Proof of original title

If the square of x equals 64, then x equals (); if the third power of x equals minus 64, then x equals (); if the eighth power of x equals 1, then x equals ()

If the square of x equals 64, then x equals (± 8); if the third power of x equals minus 64, then x equals (minus 4); if the eighth power of x equals 1, then x equals (± 1)

If f (x) = loga (x + 1) (a ＞ 0, a ≠ 1) is [0, 1], then a is equal to ()
A. 13B. 2C. 22D. 2

The definition field of F (x) = loga (x + 1) is [0, 1]; if 0 ≤ x ≤ 1, then 1 ≤ x + 1 ≤ 2. When a > 1, 0 = loga1 ≤ loga (x + 1) ≤ loga2 = 1, ｜ a = 2; when 0 < a < 1, loga2 ≤ loga (x + 1) ≤ loga1 = 0, which is contradictory to the value field [0, 1]

If the length of a rectangle increases by 4cm and the width decreases by 1cm, the area remains unchanged; if the length decreases by 2cm and the width increases by 1cm, the area remains unchanged, the area of the rectangle is______ ．

Let the length of the rectangle be xcm and the width be YCM. According to the meaning of the question, we get (x + 4) (Y − 1) = XY (x − 2) (y + 1) = XY. The solution is x = 8y = 3, so xy = 8 × 3 = 24. Answer: the area of the rectangle is 24cm2. So the answer is 24cm2