Answer:
7) x = 9°
8) x = 5°
9) x = 10°
10) x = 12°
Explanation:
7) By the angle subtended at the center is twice the angle subtended at the circumference, we have;
∠JLM = ∠JKV = 55°/2 = 27.5°
Similarly;
∠JML = ∠JVK = (18·x + 13)/2 = 9·x + 6.5
By exterior angle theory, we have;
13·x - 2 = 27.5 + 9·x + 6.5 = 9·x + 34
13·x - 9·x = 34 + 2 = 36
4·x = 36
x = 36/4 = 9
x = 9°
8) By the theorem angle formed on the outside of the circle by a tangent and a secant is equal to the difference of the arcs formed in between by the intercept of the tangent and the secant and the circle multiplied by half
Therefore;
8·x + 8 = (1/2) × (170° - (15·x - 1))
8·x + 8 = 85° - 7.5·x + 1/2
8·x +7.5·x = 85° - 8 + 1/2 = 77.5°
15.5·x = 77.5
x = 77.5°/15.5 = 5°
x = 5°
9) ∠TEU = ∠TWV = 175°/2 = 87.5°
∠TUU = ∠TYV = (5·x - 5)/2 = 2.5·x - 2.5
115° = 87.5° + 2.5·x - 2.5 = 90° + 2.5·x
2.5·x = 115° - 90° = 25°
x = 25°/2.5 = 10°
x = 10°
10) The measure of the intercepted arc formed by a chord is equal to twice the measure of the angle the chord forms with a tangent it intersects at the tangent point;
21·x + 18 = 2 × (The supplementary angle to ∠STU)
The supplementary angle to ∠STU = 180° - 45° = 135°
∴ 21·x + 18 = 2 × 135° = 270°
21·x = 270 - 18 = 252
x = 252/21 = 12
x = 12°.
