Cho hình bình hành ABCD tâm O . CMR: a) AO+ BO +CO +DO = 0. b) AB +CA =DA .c) AO+ BO =BC . d) AO- BO= DC . e) AO- BO =CD .

At a kentucky friend chicken, a survey showed 2/3 of all people preferred skinless chicken over the regular chicken. if 2,400 people responded to the survey, how many people preferred regular chicken?

Cone a has a surface area of 384 ft2 and cone b has a surface area of 96 ft? . what is the ratio of their volume?

What is the point of inflection for the function f(x)=2cos4x on the interval (0, pi/2)