What is the measure of angle R?

Option B:

25 degrees

Solution:

Given data in triangle PQR,

The side opposite to angle P is p.

The side opposite to angle Q is q.

The side opposite to angle R is r.

q = 36, r = 20, angle Q = 50°.

To find the measure of angle R:

Using law of sine,

Take only two sides.

Substitute the given values.

Do cross multiplication.

sin 50° = 0.766

⇒ R = 25.18°

⇒ R = 25° (approximately)

Option B is the correct answer.

Hence the measure of angle R is 25 degrees.

geometry: triangles

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answers archive

call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584