Student or Learner
Random House-A Dictionary of Contemporary American Usage (1957), all:
All the angles in a triangle are less than 180 degrees.
I had thought we should say 'All the angles in a triangle are (= add up to) 180 degrees' and so was very surprised to read the 'less than' in this sentence. To me 'less than 180' means '<180'. But how can the three angles be '<180 degrees'?
Could I ask native speakers to help me please? Thank you in advance.
"All the angles are ..." does not mean "All the angles add up to ...".
If all the angles in a triangle are 60 degrees, you have an equilateral triangle, having (like all triangles) 180 degrees.
All the girls in the family are less than 10 years old. They are 3, 5 and 7.
Their combined age is 15, but they are all under 10.