State and prove Pythagoras theorem.
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Answered by
23
Answer:
Statement: In a right angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides.
Given: ABC is a triangle in which ∠ABC=90
∘
Construction: Draw BD⊥AC.
Proof:
In △ADB and △ABC
∠A=∠A [Common angle]
∠ADB=∠ABC [Each 90
∘
]
△ADB∼△ABC [A−A Criteria]
So,
AB
AD
=
AC
AB
Now, AB
2
=AD×AC ..........(1)
Similarly,
BC
2
=CD×AC ..........(2)
Adding equations (1) and (2) we get,
AB
2
+BC
2
=AD×AC+CD×AC
=AC(AD+CD)
=AC×AC
∴AB
2
+BC
2
=AC
2
[henceproved]
Answered by
4
________ Answer _______
☆☆☆☆☆☆Important ☆☆☆☆☆☆
Theroem :- 1
= 》 If a perpendicular is drawn
from the vertex of the right
angle to the hypotenuse then
triangles on the both side of the
perpendicular are similar to the
whole triangle and to each other.
☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆
Pythagoras Theorem
=》In a right triangle ,the square
of hypotenuse is equal to the sum
of the squares of the other
two sides.
《《___________________________》》
Proof : We are given a right triangle ABC right angled at B.
We need to prove that AC²= AB² + BC²
Let us draw BD ⊥ AC (see Fig.)
Now, ∆ ADB ~ ∆ ABC. (Theorem 1)
So,
AD/AB =AB/AC (Sides are proportional)
or, AD . AC = AB2. ........(1)
Also, ∆ BDC ~ ∆ ABC (Theorem 6.7)
So,
CD/BC =BC/AC
or, CD ×AC = BC² .........(2)
Adding (1) and (2),
=> AD . AC + CD . AC = AB² + BC²
=> AC (AD + CD) = AB² + BC²
=> AC . AC = AB² + BC²
=> AC² = AB² + BC²
Hence, proved
__________××××__________
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