Please help! I thought it was 90º but it says thats wrong.

Step-by-step explanation:

I posted a picture at the bottom of the post that you need to look at in order to understand this problem. I labeled everything inside that circle and then created a triangle. That triangle is made up of 3 sides that are all the same length, and that length is the length of the radius. By definition, if a triangle has all 3 of its sides the same length, it is equilateral. It is also equiangular. That means that every angle inside that triangle measures 60 degrees. The central angle, the one that comes off the center, intercepts an arc. The arc measure is the same measure as this angle, so the intercepted arc measures 60 degrees. To find the measure of the angle in question, the one you need that is labeled with a pink θ, has a rule that says the angle is going to be half the measure of the intercepted arc. That means that your angle is going to measure 30 degrees.

the value of x is 9 ⇒ answer b

step-by-step explanation:

* we can solve this problem using cosine and sine rule

- in δ abc

∵ ab = 36 , bc = 28 , ac = 16

- lets find the measure of angle b using the cosine rule

∵ cos b = [ab² + bc² - ac²]/2(ab)(bc)

∴ cos b = [36² + 28² - 16²]/2(36)(28)

∴ cos b = 19/21

∴ m∠b = cos^-1(19/21) ≅ 25°

- lets find the measure of angle a using the sine rule

∵ sina/bc = sinb/ac = sinc/ab

∴ sina/28 = sin25°/16 ⇒ by using cross multiplication

∴ sina = 28 × sin25°/16

∴ sina = 0.7396

∴ m∠a = sin^-1(0.7396) ≅ 48°

- from the figure m∠abd = m∠dbc

∵ m∠abc = 25°

∴ m∠abd = 25°/2 = 12.5°

- in δabd

∵ m∠a = 48° , m∠abd = 12.5°

∵ the sum of the measures of the interior angles of any δ is 180°

∴ m∠adb = 180° - (48° + 12.5°) = 119.5°

∵ ab = 36

∵ ad = x

- use the sine rule to find x

∵ sin∠adb/ab = sin∠abd/x

∴ sin119.5°/36 = sin12.5°/x ⇒ by using cross multiplication

∴ x = 36 × sin12.5°/sin119.5° = 8.95 ≅ 9

* the value of x is 9