If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

# CA Geometry: More on congruent and similar triangles

17-20, more similar and congruent triangles. Created by Sal Khan.

## Want to join the conversation?

• if something is congruent, then wouldn't it always be similar?
(1 vote)
• Yes, congruency is a special case of similarity, just like a square is a special case of a rectangle. Congruency occurs when the scale factor is 1.
• So, are you saying that similar is when the sides and angles are equvilant, then what does congrurent mean.
(1 vote)
• Similar means that only the angles are the same, but the sides are not. Congruent means the angles and sides are the same.
(1 vote)
• what does it mean when triangles are proportional?
(1 vote)
• it means that they are similar, not congruent
(1 vote)
• When two similar triangles are in a problem are they always listed as corresponding triangles? For example similar triangles ABC and DEF .. AB=DE and so on?
(1 vote)
• hat dose porportional mean
(1 vote)
~Natalie Cooper
(1 vote)
• What do you know about the angles or lines
in the diagram? How can you use what you
know? What do you need to find out?
(1 vote)
• it all the depends on the problem some problems what you to draw out the angle on the graph it gives you
(1 vote)
• What are 30-60-90 triangles, from problem 17?
(1 vote)
• 30-60-90 triangles are special right triangles. These special triangles have angle measures of 30, 60 and 90 degrees. They have a special property that if the length opposite the 30 degree angle is x, then the length opposite the the 60 degree angle is x*sqrt(3), and the length opposite the 90 degree angle is 2x. Since 30-60-90 triangles are so special, it helps to memorize the properties of them.
(1 vote)
• For #18 even though the shapes are different its congruent anyways , right?
(1 vote)
• At - it is not possible for a triangle to have exactly one acute angle, in any circumstance. There can be two or three, but never one.
(1 vote)