Answer:
Options b and D
Explanation:
It's a question of Boolean's algebra
We will find the truth values of each statement p, q, r, and s first.
p : An isosceles triangle has two congruent sides.
Means truth value is True
q ; A right angle measures 90°
Truth value of this statement will be True
r : Four Points are always coplanar.
Truth value of this statement will be False.
s : A decagon has 12 sides
Truth value of the statement will be False.
Now we come to the options.
a. Four points are always coplanar and a right angle measures 90°.
Here "and" means conjunction and truth value of conjuncion of two statements will be true if only both the statements are true.
r q r ∧ q
T T T
But the truth value is given as false so not the correct option.
b. Four points are always coplanar and a right angle measures 90°.
As we have discussed in option a. truth value of the conjunction is True so this option will be the correct option.
c. Four points are always coplanar or a right angle measures 90°
OR means it's a disjunction and truth value of disjunction is false only when both the statements are False.
r q r ∨ q
T T T
But the truth value is given as False, so this option is not correct.
d. Four points are always coplanar or a right angle measure 90°
As discussed in option c. Truth value will be True. so this option will be the correct option.
Options b and d are the correct options.