answer:The definition of a regular pyramid is that its base is a regular polygon, and its apex projects onto the center of the base polygon. Based on this definition, we can determine: (1) The lateral faces of a regular pyramid being equilateral triangles is incorrect; (2) The lateral faces of a regular pyramid being isosceles triangles is correct; (3) A pyramid with a regular polygon as its base being a regular pyramid is incorrect; (4) All dihedral angles between the lateral faces and the base of a regular pyramid being equal is correct. Therefore, the correct choice is boxed{text{D}}.

answer:According to the 0.618 method, the amount added for the first trial is: 70 - (70 - 60) times 0.618 = 63.82, Therefore, the answer is: boxed{A}

answer:Let's call the two numbers a and b. We are given the following equations: 1) a + b = 40 2) ab = 375 3) a - b = x We need to find the values of a, b, and x. From equation 1, we can express b in terms of a: b = 40 - a Now we can substitute this expression for b into equation 2: a(40 - a) = 375 40a - a^2 = 375 Rearrange the equation to form a quadratic equation: a^2 - 40a + 375 = 0 Now we can solve for a using the quadratic formula: a = [40 ± sqrt(40^2 - 4*1*375)] / (2*1) a = [40 ± sqrt(1600 - 1500)] / 2 a = [40 ± sqrt(100)] / 2 a = [40 ± 10] / 2 This gives us two possible solutions for a: a = (40 + 10) / 2 = 50 / 2 = 25 a = (40 - 10) / 2 = 30 / 2 = 15 Since a + b = 40, we can find the corresponding values for b: If a = 25, then b = 40 - 25 = 15 If a = 15, then b = 40 - 15 = 25 So the two numbers are 25 and 15. Now we can find the value of x, which is the difference between the two numbers: x = a - b If a = 25 and b = 15, then x = 25 - 15 = 10 If a = 15 and b = 25, then x = 15 - 25 = -10 However, since x represents the difference and the order of subtraction doesn't matter for the absolute difference, we can say that x = 10. Therefore, the two numbers are 25 and 15, and the value of x is boxed{10} .

answer:Let's analyze each statement step by step: **A**: The ordinate of a point refers to its y-coordinate. For any point on the x-axis, its y-coordinate is indeed 0. Thus, statement A is correct. **B**: The distance from a point to the y-axis is given by the absolute value of its x-coordinate. For the point P(-1,3), the distance to the y-axis is |-1| = 1. Therefore, statement B is correct. **C**: For a point Q(x,y), if xy < 0, it means one of the coordinates is positive and the other is negative, since the product of a positive and a negative number is negative. Additionally, if x - y > 0, it implies x > y. If x is positive and y is negative (which satisfies xy < 0), then Q(x,y) is indeed in the fourth quadrant. Thus, statement C is correct. **D**: Analyzing the coordinates of point A(-a^{2}-1,|b|): - The x-coordinate is -a^{2}-1. Since a^{2} geq 0 for any real number a, -a^{2} leq 0. Therefore, -a^{2}-1 < 0. - The y-coordinate is |b|, which is always non-negative (|b| geq 0). Given these conditions, the point A(-a^{2}-1,|b|) must have a negative x-coordinate and a non-negative y-coordinate. This places point A either on the negative x-axis (if |b|=0) or in the second quadrant (if |b|>0). The original statement claims that point A must be in the second quadrant, which overlooks the possibility of A being on the x-axis if |b|=0. Therefore, statement D is incorrect because it does not account for all possibilities. Hence, the incorrect statement is: [boxed{D}]