Answer:
5 cm
Step-by-step explanation:
We khow that the altitude of this triangle is 1cm shorter than the base
- Let H be our altitude and B our base and A the area of the triangle
- A= (B*H)/2 ⇒ 15=(B*H)/2
- H is 1cm shorter than B ⇒ B=H+1
- H*(H+1)/2=15 ⇒ H*(H+1)=30⇒ H²+H=30⇒H²+H-30+0
that's a quadratic equation . Let's calculate the dicriminant .
Let Δ be the dicriminant
- a=1
- b=1
- c= -30
- Δ=b²-4*a*c = 1²-4*1*(-30)=1+4*30=121≥0
- Δ≥0⇔ that we have two solutions x and y
- x= (-1-
)/2= (-1-11)/2= -6 - y= (-1+
)/2= 10/2 = 5
We have a negative value and a positive one
The altitude is a distance so it can't be negative
H= 5cm
On #29 x = 12 and <apb = 90° and <dcb = 40° and on #30 all I dont even understand, sorry
Answer:
The value of y is y=15
Step-by-step explanation:
We have:
AB = 6y – 3, BC = 4y – 5, and CD = 7y – 18
We define the isosceles trapezoid as it has two opposites parallel, the two other opposites legs are equal and also the diagonals are equal.
Here AB = CD
6y-3 = 7y-18
Combine the like terms:
18-3 = 7y-6y
15 = y
It means the value of y is y=15....
Answer:
3. 9x
4. D. -5v + 4
Step-by-step explanation:
3. (-3+12)v
= 9v
4. Combine like terms:
(-2v - 3v) + (8 - 4)
= -5v + 4