Let △ ABC, cosa = 35, SINB = 513, then the value of COSC is () A. 5665b. − 1665c. 1665d. 5665 or − 1665

Let △ ABC, cosa = 35, SINB = 513, then the value of COSC is () A. 5665b. − 1665c. 1665d. 5665 or − 1665

Because in △ ABC, cosa = 35, SINB = 513 ＜ 12, Sina = 45 ＞ 22, so a ＞ π 4, B ＜ π 6 & nbsp; or B ＞ 5 π 6 (rounding off).. CoSb = 1213, so COSC = - cos (a + b) = - cosacosb + sinasinb = - 35 × 1213 + 45 × 513 = - 1665, so B is selected

Among the natural numbers within 10, () is even but not composite, odd and not prime

Among the natural numbers within 10, (2) are even numbers but not composite numbers, odd numbers and not prime numbers are (1) and (9)

The image of the first-order function Y1 = K1 + 2 and the inverse scale function y2 = K2 / X intersects at points a (4, m) and B (- 8, - 2), and intersects with the y-axis at point C

Because B (- 8, - 2) is on y = K2 / x, so K2 = 16, the analytic expression of inverse proportional function is y = 16 / X. because B (- 8, - 2) is on y = K1X + 2, so K1 = 1 / 2, the analytic expression of primary function is y = 1 / 2x + 2, because a is on y = 16 / x, so m = 4. A (4,4). The intersection of primary function y = 1 / 2x + 2 and Y axis is C (0,2), s △ AOB = s △ AOC + s △ BOC = 1 / 2 × 2 × (4 + 2) = 6

Synonym conversion
Synonyms of large
Synonyms of medium

Big / huge / enomous
Middle, a synonym for medium

If the equation of symmetry axis of parabola y = x square + MX + 1 is x = 2, then M = () a.4 B. - 4 C.1 D. - 1

The axis of symmetry of parabola y = x & # 178; + MX + 1 is x = - (M / 2) = 2, so m = - 4
Select [b]

First simplify and then evaluate the quadratic power of (2a-3b) + 4B (a-3b), where a = 2, B = 1 / 2

The second power of (2a-3b) + 4B (a-3b)
=4a²-12ab+9b²+4ab-12b²
=4a²-8ab-3b²
=4×4-8-3/4
=8-3/4
=7 and 1 / 4
Have a good time

It is known that the quadratic function f (x) = ax ^ 2 + BX + C (ABC is a real number) satisfies the following conditions:
1、f(-1)=0
2. For any real number x, f (x) - x > = 0
3. When x belongs to (0,2), there is f (x)

Substituting x = 1 into 2,3, we get f (1) = 1
b=1／2
3. The formula in can be reduced to
ax²＋1／2x＋1／2﹣a≤1／4x²﹢1／2x﹢1／4
﹙a－1／4﹚﹙x²－1﹚≤0
a=1／4,c＝1／4
The third question is OK

(1) The square of - x + 2x + 8
(2) The square of a - the square of B + the square of 2bc-c
(3) The square of X + 6xy + 8y
(4) Square of M + square of 2mn-15n
(5) square of (a-b) - (a-b) - 2
(6) Square of (a + b) + (a + b) - 6
(7) Square of a-2ab + square of B-1

1) - X's square + 2x + 8 = - (x ^ 2-2x-8) = - (x-4) (x + 2) (2) a's Square - B's square + 2bc-c's Square = a ^ 2 - (b ^ 2-2bc + C ^ 2) = a ^ 2 - (B-C) ^ 2 = (a-b + C) (a + B-C) (3) x's square + 6xy + 8y's Square = (x + 2Y) (x + 4Y) (4) M's square + 2mn-15n's Square = (m-3n) (M + 5N) (5) (...)

If the vertex coordinates of the image of a quadratic function are (1,2) and pass through (3,0.5), then the quadratic function is ()

Let the quadratic function be y = a (x-1) + 2
0.5=a(3-1)
2a=0.5
a=0.25
So the quadratic function is y = 0.25 (x-1) + 2

Solving equation (collocation method) 2x ^ - 4x + 1 = 0

2x²-4x+1 = 0
2(x²-2x+1) - 1=0
2(x-1)² - 1 = 0
(x-1)² = 1/2
x-1 = ± (√2)/2
x = 1± (√2)/2
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