Ask high school what mathematical formulas are helpful for junior high school to solve geometry?

Sine theorem a/sinA=b/sinB=c/sinC=2R Note: where r represents the radius of the circumscribed circle of a triangle.

Cosine theorem B 2 = A 2+C 2-2 AC COSB note: angle b is the included angle between side a and side C.

The standard equation of a circle (X-A) 2+(Y-B) 2 = R2 Note: (A, B) is the center coordinate.

General equation of circle x 2+y 2+dx+ey+f = 0 note: d 2+e 2-4f > 0.

Lateral area of cylinder S=c*h=2pi*h lateral area of cone s =1/2 * c * l = pi * r * l.

The arc length formula l=a*r a is the radian number r > of the central angle; 0 sector area formula s= 1/2*l*r

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