please help me to deal this question~~ thanks~~five touching circles each have radius 1 and their centres are at the vertices of a regular pentagon . What is the radius of the circle through the touching points? A.tan18 B.tan36 C. tan45 D.tan54
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/03 12:51:04
![please help me to deal this question~~ thanks~~five touching circles each have radius 1 and their centres are at the vertices of a regular pentagon . What is the radius of the circle through the touching points? A.tan18 B.tan36 C. tan45 D.tan54](/uploads/image/z/7333844-68-4.jpg?t=please+help+me+to+deal+this+question%7E%7E+thanks%7E%7Efive+touching+circles+each+have+radius+1+and+their+centres+are+at+the+vertices+of+a+regular+pentagon+.+What+is+the+radius+of+the+circle+through+the+touching+points%3F++A.tan18++++B.tan36++C.+tan45++D.tan54)
please help me to deal this question~~ thanks~~five touching circles each have radius 1 and their centres are at the vertices of a regular pentagon . What is the radius of the circle through the touching points? A.tan18 B.tan36 C. tan45 D.tan54
please help me to deal this question~~ thanks~~
five touching circles each have radius 1 and their centres are at the vertices of a regular pentagon . What is the radius of the circle through the touching points?
A.tan18 B.tan36 C. tan45 D.tan54 E tan 72
please help me to deal this question~~ thanks~~five touching circles each have radius 1 and their centres are at the vertices of a regular pentagon . What is the radius of the circle through the touching points? A.tan18 B.tan36 C. tan45 D.tan54
应该是 B
tan54
each angle of the pentagon is 108 degrees
then an right angle edge of a right triangle is 1 in length ,and this edge is a circles radius
then tan54=l/1 l=tan54
说汉语,