Question

Two sides of a triangle are 7 and 9. Which of the following could NOT be the measurement of the third side?

A.15
B. 8
C. 5
D. 1

Answer 1

think of those sides as two sticks

Answer 2

one stick is 7 inch
another stick is 9 inch

Answer 3

now tell me, if i give you a third stick of 1 inch, and ask you to make a triangle, will u be able to do that ?

Answer 4

not at all

Answer 5

that 1 inch stick is too small. it cannot make a triangle with 7 and 9.

Answer 6

for third side, you need more than 2 inch to make a triangle !

Answer 7

oh ok well that one seemed to be a no brainer :p lol thank you, so i have another similar one thats asking if i have a triangle with two sides of 6 which couldnt be the third..10, 11, & 12

Answer 8

here is the formula :-

Answer 9

third side must be LESS than the sum of first and second sides

Answer 10

since you have two sides each of 6,

third side must be LESS than 6+6

Answer 11

third side must be LESS than 12

Answer 12

so its between 10 & 11

Answer 13

is 10 less than 12 ?

Answer 14

is 11 less than 12 ?

Answer 15

yes right ? so they can make a triangle. no problem