Sinα= opposite side: hypotenuse cosα= adjacent side: hypotenuse tanα= opposite side: adjacent side sin α = cos (90-α)

Formulas for calculating circles and sectors

Arc length formula L=nπr/ 180 Sector area formula s Sector =nπr? /360= 1/2L arc length r conic side development diagram fan-shaped central angle formula n=360r/= 180L/π conic lateral area formula s side =πrL.

Total cone area =πr? =πrL

function

linear function

When k >, Y=kx+b(k≠0k, b is constant); At 0, y increases with the increase of x and k.

inverse proportion function

Y=k/x(k≠0) The image is hyperbola.

quadratic function

General formula y=ax? +bx+c(a≠0)a determines the opening direction, and the symmetry axis is the vertex coordinates (-b/2a, 4ac-b? /4a)

Translation problem: add left and subtract right, add up and subtract down.

Vertex y=a(x-h)? +k vertex (h, k)

Intersect with the x axis so that y = 0；; Intersect with the y axis so that x=0.

Two important formulas a? -B? =(a+b)(a-b)a？ +2ab+b？ =(a+b)？ Answer? -2ab+b？ =(a-b)？