Fermi
·
Concept Library
·
Courses
·
Books
·
Problems
·
Simulations
·
Math Wiki
·
High School
Fermi
›
Problems
Problem
Problem
In any
Δ
A
B
C
\Delta ABC
Δ
A
B
C
, show that
cos
A
+
cos
B
+
cos
C
=
(
1
+
r
R
)
\cos A + \cos B + \cos C = \left(1 + \frac{r}{R}\right)
cos
A
+
cos
B
+
cos
C
=
(
1
+
R
r
)
.
Browse the problem library