Question

Given: Circle k(O), diameter US , m RU=50°, m UT=30° Find: m∠RUS, m∠STU

Answer 1

Answer:

angle RUS = 65 degrees

angle STU = 90 degrees

Step-by-step explanation:

(a) find angle RUS

Given arc RU = 50 degrees, so angle RSU = 50/2 = 25 degrees

Since US is the diameter,

angle URS is a right-angle.

Consider triangle RUS,

sum of angles of a triangle = 25+90+RUS = 180  

solve for

RUS = 180 - 25 - 90 = 65 degrees.

(b) Find STU

All diameters span a right angle at the circumference,

since we're given US is a diameter, this means that

angle STU is a right angle.

Answer 2

Answer:

$\boxed{m$

Step-by-step explanation:

Finding m∠RUS:

Given that RU = 50°, So Central Angle ROU = 50° too because the measure of arc is equal to its central angle

Now, Let's assume a triangle ROU. It is an isosceles triangle since RO = RU (Radii of the same circle)

So,

∠ORU ≅ ∠OUR (Angles opposite to equal sides are equal)

So, we can write them as 2(∠RUO)

So,

2(∠RUO)+50 = 180 (Interior angles of a triangle add up to 180)

2(∠RUO) = 180-50

2(∠RUO) = 130

Dividing both sides by 2

∠RUO = 130/2

∠RUO = 65 degrees

m∠RUS = 65 degrees  (Both are the same)

Finding m∠STU now:

In a semi circle (Given that SU is a diameter) , there must be a 90 degrees angle sin it opposite to the diameter.

So,

m∠STU = 90 degrees