Question

What is the ratio of the length of DE to the length of BC ?

A. 1/4



B. 1/3



C. 2/5



D. 1/5

Answer 1

Answer: A. 1/4

Explanation:

Answer 2

Look at the picture.

`CB=(2\beta)/(180^o)\cdot\pi r=(\pi r\beta)/(90^o)\\\\DE=(\beta)/(180^o)\cdot \pi\cdot(r)/(2)=(\pi r\beta)/(360^o)\\\\(DE)/(BC)=DE:BC=(\pi r\beta)/(360^o):(\pi r\beta)/(90^o)=(\pi r\beta)/(360^o)\cdot(90^o)/(\pi r\beta)=\boxed{(1)/(4)}`

Answer: A. 1/4