Point a is the center of this circle.

the ratio of the lengths of (ef/bc) and (ad/ih) is 2: 1.

Given is a circle A with points B, C, D, E, F, and I on its circumference.

A line joining any two points on circumference of any circle is called a chord of the circle. Here BC, EF, and HI are chords of the circle.

A line joining center A and any point on circumference of the circle is called radius of the circle. Here AD is the radius of the circle.

Any chord that is passing through the center of the circle is called the diameter of the circle. Here EF and HI are diameters of the circle.

A diameter is always twice the length of radius. So ratio of diameter to radius will be 2:1.

Hence, ratio of the lengths EF and AD will be 2:1

step-by-step explanation:

y=mx+b

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.