Focus on triangles DFC and DFE:
- They are both right triangles because DF is perpendicular to EC
- DC=DE
- DF is a common side
So, the two triangles are congruent. It follows that CF=FE, and in particular

And since x=3, the length of EF is

3+(-4)=(-1)
so, 3 is the missing number
Hello :
sin<span>θ = 15/17
</span> use pythagorean identity : cos²θ +sin² θ = 1
cos²θ = 1 - sin² θ
cos²θ = 1-(15/17)²
cos²θ = 1- 225/289
cos²θ = 64/289
cos²θ = (8/17)²
cosθ = 8/17 or -8/17
Answer:
m<G = 71
Step-by-step explanation:
Find x first
7x + 1 + 6x - 6 + 55 = 180
Combine like terms:
13x + 50 = 180
- 50 - 50
13x = 130
/13 /13
x = 10
Then apply to problem
7 (10) + 1
70 + 1
= 71