Question

I am having trouble figuring out when to use SAS, SSS, ASA and AS postulates. Examples: http://i.imgur.com/uP4xP7P.png I can see how SSS or SAS could be the answer but I don't know which one I'm supposed to use. http://i.imgur.com/czkBNRh.png I don't know if I should use SSS, SAS, or AS.

Answer 1

to find the postulates youll need to now th hl postulate and the la postulates

Answer 2

You use SAS, SSS, etc to show two triangles are congruent (same size and shape, i.e. identical)
But this problem has two triangles that are *not* congruent. The two triangles are similar (their corresponding angles are equal)

Answer 3

thus you could use "corresponding parts of similar triangles" to write a ratio
of the sides of the little triangle and the "big" outer triangle.

For example, the ratio of left side to bottom side
the small triangle has 5 for the left and 10 for the bottom
the big triangle has left side 5+2.5= 7.5 and x (unknown) for the bottom
write the ratio
\[ \frac{10}{5} = \frac{x}{7.5} \]
simplify the left ratio to 2
\[ 2= \frac{x}{7.5} \]

Answer 4

multiply both sides by 7.5 to get
2*7.5 = x
or
x= 15
in other words, the bottom side of the big triangle is 15