Respuesta :
Answer:
1. m∠R > 90°
2. m∠S + m∠T < 90°
4. m∠R > m∠T
5. m∠R > m∠S
Step-by-step explanation:
General strategy
- prove the statement starting from known facts, or
- disprove the statement by finding a counterexample
Helpful fact: Recall that the Triangle Sum Theorem states that m∠R + m∠S + m∠T = 180°.
Option 1. m∠R > 90°
Start with m∠R > m∠S + m∠T.
Adding m∠R to both sides of the inequality...
m∠R + m∠R > m∠R + m∠S + m∠T
There are two things to note here:
- The left side of this inequality is 2*m∠R
- The right side of the inequality is exactly equal to the Triangle Sum Theorem expression
2* m∠R > 180°
Dividing both sides of the inequality by 2...
m∠R > 90°
So, the first option must be true.
Option 2. m∠S + m∠T < 90°
Start with m∠R > m∠S + m∠T.
Adding (m∠S + m∠T) to both sides of the inequality...
m∠R + (m∠S + m∠T) > m∠S + m∠T + (m∠S + m∠T)
There are two things to note here:
- The left side of this inequality is exactly equal to the Triangle Sum Theorem expression
- The right side of the inequality is 2*(m∠S+m∠T)
Substituting
180° > 2* (m∠S+m∠T)
Dividing both sides of the inequality by 2...
90° > m∠S+m∠T
So, the second option must be true.
Option 3. m∠S = m∠T
Not necessarily. While m∠S could equal m∠T, it doesn't have to.
Example 1: m∠S = m∠T = 10°; By the triangle sum Theorem, m∠R = 160°, and the angles satisfy the original inequality.
Example 2: m∠S = 15°, and m∠T = 10°; By the triangle sum Theorem, m∠R = 155°, and the angles still satisfy the original inequality.
So, option 3 does NOT have to be true.
Option 4. m∠R > m∠T
Start with the fact that ∠S is an angle of a triangle, so m∠S cannot be zero or negative, and thus m∠S > 0.
Add m∠T to both sides.
(m∠S) + m∠T > (0) + m∠T
m∠S + m∠T > m∠T
Recall that m∠R > m∠S + m∠T.
By the transitive property of inequalities, m∠R > m∠T.
So, option 4 must be true.
Option 5. m∠R > m∠S
Start with the fact that ∠T is an angle of a triangle, so m∠T cannot be zero or negative, and thus m∠T > 0.
Add m∠S to both sides.
m∠S + (m∠T) > m∠S + (0)
m∠S + m∠T > m∠S
Recall that m∠R > m∠S + m∠T.
By the transitive property of inequalities, m∠R > m∠S.
So, option 5 must be true.
Option 6. m∠S > m∠T
Not necessarily. While m∠S could be greater than m∠T, it doesn't have to be. (See examples 1 and 2 from option 3.)
So, option 6 does NOT have to be true.
Answer: Option 1, 2, 4, & 5 or
A. m∠R > 90°; B. m∠S + m∠T < 90°; D. m∠R > m∠T; & E. m∠R > m∠S
Step-by-step explanation: Trust Me!
- m∠R > 90°
- m∠S + m∠T < 90°
- m∠R > m∠T
- m∠R > m∠S
If you are working on Edge the answer is correct. The proof is down below. I hope someone finds this helpful.
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