2. Points A, B and C are all on the circumference of the circle. o
represents the centre.
DA and DB are tangents to the
circle. Angle BDO = 31
Work out the size of angle.

Question

Points A, B and C are all on the

circumference of the circle. O represents the centre. DA and DB are tangents to the circle. Angle BDO = 31°

Work out the size of angle x

62°

Step-by-step explanation:

To solve for the above question, we would be using circle theorems.

Step 1

Angle OBD = 90° This is because a radius and a tangent meet at 90°

Step 2

The sum of Angles in a triangle = 180°

180° = Angle OBD + Angle BDO + Angle BOD

180° = 90° + 31° + Angle BOD

Angle BOD = 180° - (90° + 31°)

= 180° - 121°

Angle BOD = 59°

Step 3

Angle BOD = Angle AOD because they are congruent ,therefore, Angle AOD = 59°

Step 4

The sum of angles of a straight line = 180°

Angle BOD, Angle AOD and Angle x are angles on a straight line

Hence,

180° = Angle BOD + Angle AOD + Angle x

180° = 59° + 59° + x

x = 180° - ( 59 + 59)°

x = 180° - 118°

x = 62°

Therefore Angle x = 62°

x = central angle apc = measure of minor arc ac

the two angles x and 30 add to 180, so x+30 = 180 and x = 180-30 = 150. the measure of minor arc ac is 150 degrees.

what we need to do from here is find the circumference and then multiply it by x/360 since there are 360 degrees in a circle. in this case, x = 150, so x/360 = 150/360 = 15/36 = 5/12. the shortest distance along the curve from a to c is 5/12 of the distance around the entire circle (aka circumference)

c = circumference

c = pi*d

c = pi*24

c = 24pi

now multiply this by 5/12 to get

distance along minor arc ac = (5/12)*(circumference)

distance along minor arc ac = (5/12)*(24pi)

distance along minor arc ac = 10pi

the formula you can use is

l = (x/360)*pi*d

with

l = length of minor arc

x = central angle

d = diameter

which essentially is the steps we took though a bit differently.

a=24; b=12

step-by-step explanation:

a/b=2: 1

a=2b

36/(1+2)=12

b=12

a=24