Isosceles Triangle and its Properties Video Lecture - Class 7

hi welcome to moomoomath today we're
gonna look at what an isosceles triangle
is and what are some of the properties
this one's a really interesting triangle
one isosceles triangle is a triangle
that has two congruent sides so in this
diagram we have these two sides marking
grid or you can have possibly the sides
like a five five let's say in four and
then you could say okay that's an
isosceles triangle because two out of
the three sides are congruent okay the
other way to look at it is in
perspective of the angles okay we see
that this angle is 45 this angles 45 and
this angles 90 since we have two angles
that are congruent that means this is an
isosceles triangle that would actually
mean if I go to the opposite side this
side and this side are the two congruent
sides or in this case they're actually
congruent legs cuz they're in a right
triangle okay so let's look at the rules
of isosceles triangles isosceles
triangle is a triangle that has two
sides that are congruent which means
equal length or two angles that are
congruent or have equal measure so it
can look like this now let's go back to
this triangle one more time I'm gonna
show you one more quick tip if this side
is five or actually let me give you up a
measure at the top let's say that we
know the angle up here is 40 degrees can
we figure out these other two angles we
can because we know that a triangle adds
to 180 degrees if I've used up 40
degrees what do I have left I have a
hundred and forty degrees left but I
also know that these two base angles are
congruent to each other so I can just
take the one forty and divide it by two
and then that gives me the angle measure
of 70 so each of these two what we call
base angles measures 70 degrees so
there's a little helpful hand with
isosceles triangles hope this was
helpful