On a Right angled triangle, number of theorem are derived. One such theorem is Mid point Theorem, with below example theorem is very well explained.
Topic : Right angle Triangle and Mid Point Theorem
Problem : Given angle C is a right angle, E is a midpoint of AC, F is the midpoint of BC, AF = √41, BE = 2√26, Find AB
Solution :
From the figure,
In ∆ACF
AC2 + CF2 = AF2 (by Pythagoras Theorem)
AC2 + (CB/2)2 = (√41)2 (as CF is half of CB)
AC2 + CB2/4 = 41
Now in ∆ECB
EC2 + CB2 = EB2
(AC/2)2 + CB2 = (2√26)2 (as EC is half of AC)
AC2/4 + CB2 = 104
Now adding both the equations, we get
AC2 + CB2/4 + AC2/4 + CB2 = 41 + 104
(1+1/4)AC2 + (1+1/4)CB2 = 145
5AC2/4 + 5CB2/4 = 145
5/4(AC2 + CB2) = 145
Now, in ∆ACB, AC2 + CB2 = AB2
So we get, 5/4 AB2 = 145
AB2 = 145 * 4/5
AB2 = 116
AB = √116
AB = 2√29
Hope the above elaborated explanation will help you to understand mid point theorem and help you to solve similar kind of problems.
If you have any queries please write to us and geometry help will respond to your queries.
Wednesday, May 6, 2009
Thursday, April 9, 2009
Question on Listing Polygon Names
Topic : Polygon
Question : List the names of Ploygons
Solution :
Sides ------ Name
n ----------N-gon
3 ----------Triangle
4 ----------Quadrilateral
5 ----------Pentagon
6 ----------Hexagon
7 ----------Heptagon
8 ----------Octagon
10 ---------Decagon
12 ---------Dodecagon
Question : List the names of Ploygons
Solution :
Sides ------ Name
n ----------N-gon
3 ----------Triangle
4 ----------Quadrilateral
5 ----------Pentagon
6 ----------Hexagon
7 ----------Heptagon
8 ----------Octagon
10 ---------Decagon
12 ---------Dodecagon
Monday, April 6, 2009
Question to Prove a Theorem
Topic : Theorem
Theorem : Prove that if gcd(a,p²)=p and gcd(b,p²)=p² then gcd(ab,p^4)=p³. where a and b are integers and p is a prime number.
Solution :
GCD (a, p²) = p
implies that a ia a multiple of p or p is a divisor of a.
So let a = kp
where k is a constant
Similarly GCD(b, p²)=p²
implies that b is the multiple of p² or p² is a divisor of b
So let b = mp²
where m is a constant
So a = kp and b = mp²
ab = kp . mp²
ab = kmp³
implies that ab is a multiple of p³ and km is the constant
So greatest common dividor of kmp³ and p^4 is p³
Hence GCD (ab, p^4) = p³
Hence proved.
Theorem : Prove that if gcd(a,p²)=p and gcd(b,p²)=p² then gcd(ab,p^4)=p³. where a and b are integers and p is a prime number.
Solution :
GCD (a, p²) = p
implies that a ia a multiple of p or p is a divisor of a.
So let a = kp
where k is a constant
Similarly GCD(b, p²)=p²
implies that b is the multiple of p² or p² is a divisor of b
So let b = mp²
where m is a constant
So a = kp and b = mp²
ab = kp . mp²
ab = kmp³
implies that ab is a multiple of p³ and km is the constant
So greatest common dividor of kmp³ and p^4 is p³
Hence GCD (ab, p^4) = p³
Hence proved.
Tuesday, March 31, 2009
Wednesday, March 25, 2009
Simple Linear Equation to Find the Value of a Variable
Topic : Linear Equation
Problem : Solve 0.7n - 1.5 + 7.3n = 14.5
Solution :
0.7n - 1.5 + 7.3n = 14.5
8.0n - 1.5 = 14.5
8.0n = 14.5 + 1.5
8.0n = 16.0
n = 16.0/8.0
n = 2.0
= n = 2
Problem : Solve 0.7n - 1.5 + 7.3n = 14.5
Solution :
0.7n - 1.5 + 7.3n = 14.5
8.0n - 1.5 = 14.5
8.0n = 14.5 + 1.5
8.0n = 16.0
n = 16.0/8.0
n = 2.0
= n = 2
Friday, March 20, 2009
Integration by Tabular Method
Topic : Integration by Tabular Method
Question : Find ∫x³ Cos 2x dx
Hints :
∫x^n Cos ax dx
Take u = x^n
dv = Cos ax dx
For patterns like
∫x^n Sin ax dx , ∫x^n Cos ax dx ,
∫x^n e^(ax) dx we use tabular method
Solution :
∫x³ Cos 2x dx
u = x³ and dv = Cos 2x
+x³(Sin 2x)/2 - 3x²(-Cos 2x)/4 + 6x(-Sin 2x)/8 - 6(Cos 2x)/16
=(x³Sin 2x)/2 + 3/4 *(x²Cos 2x) - 6/8 *(xSin 2x) - 6/16 *(Cos 2x) + c
Question : Find ∫x³ Cos 2x dx
Hints :
∫x^n Cos ax dx
Take u = x^n
dv = Cos ax dx
For patterns like
∫x^n Sin ax dx , ∫x^n Cos ax dx ,
∫x^n e^(ax) dx we use tabular method
Solution :
∫x³ Cos 2x dx
u = x³ and dv = Cos 2x
+x³(Sin 2x)/2 - 3x²(-Cos 2x)/4 + 6x(-Sin 2x)/8 - 6(Cos 2x)/16
=(x³Sin 2x)/2 + 3/4 *(x²Cos 2x) - 6/8 *(xSin 2x) - 6/16 *(Cos 2x) + c
Tuesday, March 17, 2009
Problem on Factorization
Topic : Factorization
Problem : Solve a^4 +3a^3+27a+81
Solution :
a^4 +3a^3+27a+81
First let's group the terms
(a^4 +3a^3)+(27a+81)
Now we take common factors
from each parenthesis.
a^3(a+3)+ 27(a+3) as 81/27 = 3
Again we have a common factor
(a+3)
So, (a+3)(a^3+27)
or (a+3)(a^3+3^3)
Applying the formula x^3+y^3 = (x+y)(x^2-xy+y^2) for a^3+b^3
we get (a+3)(a+3)(a^2-3a+3^2)
(a+3)(a+3)(a^2-3a+9)
or
(a+3)^2(a^2-3a+9)
Problem : Solve a^4 +3a^3+27a+81
Solution :
a^4 +3a^3+27a+81
First let's group the terms
(a^4 +3a^3)+(27a+81)
Now we take common factors
from each parenthesis.
a^3(a+3)+ 27(a+3) as 81/27 = 3
Again we have a common factor
(a+3)
So, (a+3)(a^3+27)
or (a+3)(a^3+3^3)
Applying the formula x^3+y^3 = (x+y)(x^2-xy+y^2) for a^3+b^3
we get (a+3)(a+3)(a^2-3a+3^2)
(a+3)(a+3)(a^2-3a+9)
or
(a+3)^2(a^2-3a+9)
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