Let x=ab=ac, and y=bc, and z=ad.
Since the perimeter of the triangle abc is 36, you have:
Perimeter of abc = 36
ab + ac + bc = 36
x + x + y = 36
(eq. 1) 2x + y = 36
The triangle is isosceles (it has two sides with equal length: ab and ac). The line perpendicular to the third side (bc) from the opposite vertex (a), divides that third side into two equal halves: the point d is the middle point of bc. This is a property of isosceles triangles, which is easily shown by similarity.
Hence, we have that bd = dc = bc/2 = y/2 (remember we called bc = y).
The perimeter of the triangle abd is 30:
Permiter of abd = 30
ab + bd + ad = 30
x + y/2 + z =30
(eq. 2) 2x + y + 2z = 60
So, we have two equations on x, y and z:
(eq.1) 2x + y = 36
(eq.2) 2x + y + 2z = 60
Substitute 2x + y by 36 from (eq.1) in (eq.2):
(eq.2') 36 + 2z = 60
And solve for z:
36 + 2z = 60 => 2z = 60 - 36 => 2z = 24 => z = 12
The measure of ad is 12.
If you prefer a less algebraic reasoning:
- The perimeter of abd is half the perimeter of abc plus the length of ad (since you have "cut" the triangle abc in two halves to obtain the triangle abd).
- Then, ad is the difference between the perimeter of abd and half the perimeter of abc:
ad = 30 - (36/2) = 30 - 18 = 12
-5 like minus 5 no mater the negetive for y
Hope this helped ")
Answer:
θ = π n + π/2 for n element Z
Step-by-step explanation:
Solve for θ:
1 + 2 cos(2 θ) + cos^2(2 θ) = 0
Write the left hand side as a square:
(cos(2 θ) + 1)^2 = 0
Take the square root of both sides:
cos(2 θ) + 1 = 0
Subtract 1 from both sides:
cos(2 θ) = -1
Take the inverse cosine of both sides:
2 θ = 2 π n + π for n element Z
Divide both sides by 2:
Answer: θ = π n + π/2 for n element Z
The distributive property of multiplication over addition can be used when you multiply a number by a sum. The distributive property lets you multiply a sum by multiplying each addend separately and then add the products:

The distributive property of multiplication over subtraction can be used when you multiply a number by a difference. The property states that the product of a number and the difference of two other numbers is equal to the difference of the products:

Therefore, you can see what sign is in the brackets, if sign is "+", then you have to add, if sign is "-", then you have to subtract.
Answer:
Acute Triangle
Step-by-step explanation:
<u><em>Angles in a triangle add up to 180 degrees.</em></u>
So,
x+2x+2x = 180
=> 5x = 180
Dividing both sides by 5
=> x = 36
<u><em>So, The lengths are:</em></u>
=> 36
=> 72
=> 72
<em><u>Since all the angles are less than 90 degrees, It is an acute triangle.</u></em>