Answer:
√11
Step-by-step explanation:
4 = x^2 -7
Add 7 to both sides
11 = x^2
Square root both sides
√11 = x
Cos(pi) = -1
You should have this memorized along with other values such as
sin(0) = 0
cos(0) = 1
sin(pi/2) = 1
cos(pi/2) = 0
sin(pi) = 0
cos(pi) = -1
sin(3pi/2) = -1
cos(3pi/2) = 0
and remember that tan = sin/cos
No, this is not valid. In the picture below,

is a vertical angle with

. But

is not
Answer:
To find the surface area of a cuboid, add the areas of all 6 faces. We can also label the length (l), width (w), and height (h) of the prism and use the formula, SA=2lw+2lh+2hw, to find the surface area.
Ya gotta use the Pythagorean theorem :)
a² + b² = c² (reminder: c is the hypotenuse)
4² + 8² = c²
16 + 64 = 80
√80 = 8.94
H = 8.94