Cho hình chóp SABCD. Lấy I thuộc SA, J thuộc SB sao cho IJ không song song với AB. Lấy điểm K trong miền tứ giác ABCD. Tìm đường cao tuyến của I, J, K với các mặt sau đây: ABCD, SBC, SAD, SCD

Step-by-step explanation:

25/4

step-by-step explanation:

call segment cd's length x. because dc and ab are parallel, angle acd and cab, so triangles adc and abc are similar and we can set up the equation x / ac = ac / ab, or x / 5 = 5 / 4 and x = 25/4.

18

step-by-step explanation:

draw the shape and you will see that f and k are actually at adjacent vertices (points of the hexagon that are neighboring).   so find the distance between (1,2) and (4,2).   that is easy since (1,2) and (4,2) is just a vertical distance to count, which is 3.   it is a regular polygon which means all sides are congruent.   you have 6 sides (hexa) so multiply 6 by 3 to receive 18.