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That's only true if the "legs" are indeed legs, i.e. the triangle is a right triangle, and the legs

include a 90-degree angle.

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14y ago
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12y ago

Because the included angle is always 90 degrees,

so S.A.S. is always satisfied.

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Q: Why does the LL theorem hold for proving right triangles congruent?
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What is the donkey theorem?

When trying to prove two triangles congruent, you can use SSS, SAS, ASA, AAS, HL, and HA patterns. However, the pattern A S S doesn't work. Instead of spelling or saying this word in class, you can refer to it as "the donkey theorem". You can look at the pattern in the two triangles and say "these two triangles are not congruent because of the donkey theorem." You CANNOT prove triangles incongruent with 'the donkey theorem', nor can you prove them congruent. It's mostly sort of a joke, you could say, but it's never useful. The reason is that if the two triangles ARE congruent, then of course there will be an unincluded congruent angle as well as two congruent sides. The theorem doesn't do anything left, right, forward or backward. It's not even really a theorem. :P


Which theorem is used to prove that aas triangle congruence postulate theorem?

AAS: If Two angles and a side opposite to one of these sides is congruent to thecorresponding angles and corresponding side, then the triangles are congruent.How Do I know? Taking Geometry right now. :)


What are the theorems and postulates you can use to prove triangles are congruent?

Pythagorean's Theorem is one of the most famous ones. It says that the two squared sides of a right triangle equal the squared side of the hypotenuse. In other words, a2 + b2 = c2


Show that if diagonals of a quadrilateral bisects each other then it is a rhombus?

This cannot be proven, because it is not generally true. If the diagonals of a quadrilateral bisect each other, then it is a parallelogram. And conversely, the diagonals of any parallelogram bisect each other. However not every parallelogram is a rhombus.However, if the diagonals are perpendicular bisectors, then we have a rhombus.Consider quadrilateral ABCD, with diagonals intersecting at X, whereAC and BD are perpendicular;AX=XC;BX=XD.Then angles AXB, BXC, CXD, DXA are all right angles and are congruent.By the ASA theorem, triangles AXB, BXC, CXD and DXA are all congruent.This means that AB=BC=CD=DA.Since the sides of the quadrilateral ABCD are congruent, it is a rhombus.


How do you prove that the diagonals and either base of an isosceles trapezoid form an isosceles triangle?

Consider the isosceles trapezium ABCD (going clockwise from top left) with AB parallel to CD. And let the diagonals intersect at O Since it is isosceles, AD = BC and <ADC = <BCD (the angles at the base BC). Now consider triangles ADC and BCD. AD = BC The side BC is common and the included angles are equal. So the two triangles are congruent. and therefore <ACD = <BDC Then, in triangle ODC, <OCD (=<ACD = <BDC) = <ODC ie ODC is an isosceles triangle. The triangle formed at the other base can be proven similarly, or by the fact that, because AB CD and the diagonals act as transversals, you have equal alternate angles.

Related questions

What are the four congruence theorems for a right triangle?

The four congruence theorem for right triangles are:- LL Congruence Theorem --> If the two legs of a right triangle is congruent to the corresponding two legs of another right triangle, then the triangles are congruent.- LA Congruence Theorem --> If a leg and an acute angle of a right triangles is congruent to the corresponding leg and acute angle of another right triangle, then the triangles are congruent.- HA Congruence Theorem --> If the hypotenuse and an acute angle of a right triangle is congruent to the corresponding hypotenuse and acute angle of another triangle, then the triangles are congruent.- HL Congruence Theorem --> If the hypotenuse and a leg of a right triangle is congruent to the corresponding hypotenuse and leg of another right triangle, then the triangles are congruent.


The LA theorem says that two right triangles will be congruent if they have a congruent?

leg


What is the hl theorem?

The hypotenuse leg theorem states that any two right triangles that have a congruent hypotenuse and a corresponding, congruent leg arecongruent triangles.


Assume you are given two right triangles with congruent hypotuneses and wish to show that they are congruent Which congruence theorem for right triangles that may be of use?

The HA and HL theorems for right triangles or the Pythagorean theorem might be of use.


The HA theorem requires that two right triangles have a congruent angle and a congruent?

hypotenuses


What postulate or theorem verifies the congruence of triangles?

sssThere are five methods for proving the congruence of triangles. In SSS, you prove that all three sides of two triangles are congruent to each other. In SAS, if two sides of the triangles and the angle between them are congruent, then the triangles are congruent. In ASA, if two angles of the triangles and the side between them are congruent, then the triangles are congruent. In AAS, if two angles and one of the non-included sides of two triangles are congruent, then the triangles are congruent. In HL, which only applies to right triangles, if the hypotenuse and one leg of the two triangles are congruent, then the triangles are congruent.


Which congruence theorem guarantees that right angled triangles are congruent?

The checking for right-angled triangles is RHS:Right angle - they both haver a right angleHypotenuse - the hypotenuse of the triangles are congruentSide - a corresponding side of the triangles are congruent.


What is the hypotenuse angle theorem?

The hypotenuse angle theorem, also known as the HA theorem, states that 'if the hypotenuse and an acute angle of one right triangle are congruent to the hypotenuse and an acute angle of another right triangle, then the two triangles are congruent.'


The LL theorem states that for right triangles two congruent what are sufficient to prove congruence of the triangles?

LEGS


What is LL Congruence Theorem?

LL Congruence theorem says: If the two legs of one right triangle are congruent to the two legs of another right triangle, then the two right triangles are congruent.


What does the hypotenuse-angle theorem say?

If the hypotenuse and an acute angle of a right triangle are congruent to the correspondingparts of another right triangle, then the triangles are congruent.


To use the HL theorem to prove two triangles are congruent the triangles must be right trianglesWhich other conditions must also be met?

1. There are two right triangles. 2. They have congruent hypotenuses. 3. They have one pair of congruent legs.