9514 1404 393
Answer:
D
Step-by-step explanation:
In the second quadrant, ...
c = 180° -arcsin(24/25) ≈ 106.26°
In the third quadrant, ...
d = 360° -arccos(-3/4) ≈ 221.41°
Then cos(c+d) = cos(327.67°) ≈ 0.84498
This is a positive irrational number, greater than 21/100, so the only reasonable choice is the last one:
_____
Perhaps you want to work this out using the trig identities.
cos(c) = -√(1 -sin(c)²) = -7/25
sin(d) = -√(1 -cos(d)²) = -(√7)/4
Then the desired cosine is ...
cos(c+d) = cos(c)cos(d) -sin(c)sin(d)
cos(c+d) = (-7/25)(-3/4) -(24/25)(-√7/4)
cos(c+d) = (21 +24√7)/100 . . . . matches choice D
Let's just choose "x" as our variable for the length of a side of the triangle.
Two sides of a triangle are equal in length and double the length of the shortest side.
A triangle has 3 sides. Make the smallest side x then the two equal sides that are double the smallest side are both equal to 2x
The perimeter of the triangle is 35 inches. Perimeter is the sum of all sides.
x + 2x + 2x = 35
5x = 35
x = 7
So the smallest side is 7, and the other two sides are 14.
Answer:
using Pythagoras theorem
Step-by-step explanation:
it's option c
