Mathematics for the final exam of the second year of vocational high school

1.y=4x^2+8x+7=4x^2+8x+4- 1 1=4(x+ 1)^2- 1 1

When x=- 1, the minimum value is-1 1.

2. the height d from point a is perpendicular to a, the intersection point is d, and BD = K.

When the angle c is 60 degrees, we can get D = √ 3cd = 1 > BD = 2 > C = √ 7.

Angle B = arcsine √3/√7

Let point a be the vertical line AH and the intersection point h.

Then we can get CH= 1, ah = √ 3 > BH = 1.

The angle b is arctg√3=60 degrees.