Question

Identify the measure of arc HD◠.

Answer 1

arc HD = 20°

Explanation:

Let point N be the point where secant RL intersect the circle, point M be the point of intersection for chords NL and KH, and point S be the vertex of the triangle formed by secants KH and RD.

It is given that m∠SRM = 38∘ and m∠RMS = 92∘. Use the Triangle Sum Theorem to determine m∠MSR.

m∠MSR = 180° − 92∘ − 38∘ = 50∘

It is also given that mPN = 18∘ and mNK = 102∘. So, mPK = 18∘ + 102∘ = 120∘.

If a tangent and a secant, two tangents, or two secants intersect in the exterior of a circle, then the measure of the angle formed is half the difference of the measures of its intercepted arcs. So,

m∠MSR= 1 /2 (mPK − mHD)

Substitute the known values and solve for mHD.

50∘ = 1/2 (120∘ − mHD)

Multiply by 2.

100 = 120∘ − mHD

Simplify.

mHD = 20

Therefore, the measure of arc HD is 20∘.

Answer 2

The measure of arc HD is 20°

Explanation:

we know that

The measurement of the outer angle is the semi-difference of the arcs it encompasses.

In the triangle of the figure , the measure of the third interior angle is equal to

180°-92°-38°= 50°

50°=(1/2)[(102+18)°-arc HD]

100°=[120°-arc HD]

arc HD=120°-100°=20°