A problem of solving the combination of triangle and vector In the triangle ABC, h is perpendicular, the dot product of vector BH and vector BC is 6, the sum of squares of sina and sinc = the square of SINB + Sina * sinc Find: (1) angle B (2) When the radius of circumcircle r of triangle ABC is the smallest, the shape of triangle ABC can be judged

A problem of solving the combination of triangle and vector In the triangle ABC, h is perpendicular, the dot product of vector BH and vector BC is 6, the sum of squares of sina and sinc = the square of SINB + Sina * sinc Find: (1) angle B (2) When the radius of circumcircle r of triangle ABC is the smallest, the shape of triangle ABC can be judged

Sum of squares of sina and sinc = square of SINB + Sina * sinc
a^2+c^2=b^2+ac
Compared with cosine theorem, CoSb = 1 / 2, B = 60
The angle between vector BH and vector BC is 30 degrees