Advertisements
Advertisements
Question
By giving a counter example, show that the following statements are not true.
p: If all the angles of a triangle are equal, then the triangle is an obtuse angled triangle.
Advertisements
Solution
The given statement is of the form “if q then r”.
q: All the angles of a triangle are equal.
r: The triangle is an obtuse-angled triangle.
The given statement p has to be proved false. For this purpose, it has to be proved that if q, then ∼r.
To show this, angles of a triangle are required such that none of them is an obtuse angle.
It is known that the sum of all angles of a triangle is 180°. Therefore, if all the three angles are equal, then each of them is of measure 60°, which is not an obtuse angle.
In an equilateral triangle, the measure of all angles is equal. However, the triangle is not an obtuse-angled triangle.
Thus, it can be concluded that the given statement p is false.
APPEARS IN
RELATED QUESTIONS
By giving a counter example, show that the following statements are not true.
q: The equation x2 – 1 = 0 does not have a root lying between 0 and 2.
Find out the following sentence is a statement and is not. Justify your answer.
Listen to me, Ravi !
Find out the sentence are statement and are not. Justify your answer.
All triangles have three sides.
Find out the sentence are statement and are not. Justify your answer.
This sentence is a statement.
Write the negation of the statement:
Banglore is the capital of Karnataka.
Write the negation of the statement:
Ravish is honest.
Write the negation of the statement:
The earth is round.
There is a complex number which is not a real number.
Write the negation of the statement:
q : For every real number x, either x > 1 or x < 1.
Find the component statement of the compound statement:
25 is a multiple of 5 and 8.
For statement, determine whether an inclusive "OR" or exclusive "OR" is used. Give reasons for your answer.
Students can take Hindi or Sanskrit as their third language.
Write of the statement in the form "if p, then q".
The game is cancelled only if it is raining.
Check the validity of the statement:
q : 125 is a multiple of 5 and 7.
Check the validity of the statement:
r : 60 is a multiple of 3 or 5.
statement are true and false? In each case give a valid reason for saying so
p : Each radius of a circle is a chord of the circle.
Identify the component statements and the connective in the following compound statements.
It is raining or the sun is shining.
Write the negation of the following statements:
p: All triangles are equilateral triangles.
Rewrite the following statements in the form of conditional statements:
When you sing, my ears hurt.
Identify the quantifiers and write the negation of the following statements:
There exists a number which is equal to its square.
Identify the quantifiers and write the negation of the following statements:
There exists a number which is a multiple of 6 and 9.
The negation of the statement “It is raining and weather is cold.” is ______.
Which of the following sentences are statements? Justify
Sky is red.
Which of the following sentences are statements? Justify
15 + 8 > 23
Find the component statements of the following compound statements.
Number 7 is prime and odd.
Find the component statements of the following compound statements.
Chandigarh is the capital of Haryana and U.P.
Find the component statements of the following compound statements.
A rectangle is a quadrilateral or a 5-sided polygon.
Write the component statements of the following compound statements and check whether the compound statement is true or false.
2 is an even number and a prime number.
Translate the following statements into symbolic form
A number is either divisible by 2 or 3.
Write down the negation of following compound statements
All real numbers are rationals or irrationals.
Write down the negation of following compound statements
|x| is equal to either x or – x.
Rewrite the following statements in the form of conditional statements
2b = a + c, if a, b and c are in A.P.
Identify the Quantifiers in the following statements.
There exists a real number which is not a rational number.
Identify the Quantifiers in the following statements.
For all real numbers x with x > 3, x 2 is greater than 9.
Identify the Quantifiers in the following statements.
There exists a statement in above statements which is not true.
The connective in the statement “Earth revolves round the Sun and Moon is a satellite of earth” is ______.
The negation of the statement “7 is greater than 8” is ______.
The negation of the statement “The product of 3 and 4 is 9” is ______.
