we know that
Law of detachment is used when you have a conditional statement and another statement that matches the hypothesis of the conditional.
Law of syllogism is used when you have two conditionals and the hypothesis of one matches the conclusion of the other
in this problem we have the law of detachment
the conditional statement is
If a triangle has an angle with a measure more than 90°
the another statement that matches the hypothesis of the conditional
then the triangle is an obtuse triangle
therefore
the answer is
the law of detachment