diff --git a/src/basic_operations.h b/src/basic_operations.h
index a4a4e63..8028a5b 100644
--- a/src/basic_operations.h
+++ b/src/basic_operations.h
@@ -13,6 +13,7 @@
 
 double logarithm(double num, double base)
 {
+  assert(num > 0 && base > 0 && base != 1);
   double result = log(num) / log(base);
   return result;
 }
diff --git a/src/combinatorics.h b/src/combinatorics.h
index 34e848c..77be3ea 100644
--- a/src/combinatorics.h
+++ b/src/combinatorics.h
@@ -51,7 +51,7 @@ long long cyclePermutation(int num)
 long long arrangement(int total, int selected)
 {
   long long result;
-  assert(total > 0 && selected >= 0);
+  assert(total > 0 && selected >= 0 && selected <= total);
   result = factorial(total) / factorial(total - selected);
   return result;
 }
@@ -113,7 +113,7 @@ double cyclePermutationlf(int num)
 double arrangementlf(int total, int selected)
 {
   double result;
-  assert(total > 0 && selected >= 0);
+  assert(total > 0 && selected >= 0 && selected <= total);
   result = factoriallf(total) / factoriallf(total - selected);
   return result;
 }
diff --git a/src/probability_distribution.h b/src/probability_distribution.h
index b7e061d..ffdad07 100644
--- a/src/probability_distribution.h
+++ b/src/probability_distribution.h
@@ -22,7 +22,8 @@
 double binominal(int trials, double successProb, int success)
 {
   double result;
-  assert(trials > 0 && success >= 0 && successProb >= 0 && successProb <= 1);
+  assert(trials > 0 && success >= 0 && success <= trials &&
+         successProb >= 0 && successProb <= 1);
   result = combinationlf(trials, success) *
            pow(successProb, success) *
            pow((1 - successProb), (trials - success));
@@ -39,6 +40,7 @@ double binominal(int trials, double successProb, int success)
 double poisson(double lambda, unsigned x)
 {
   double result;
+  assert(lambda >= 0);
   result = exp(-lambda) * pow(lambda, x) / factoriallf(x);
   return result;
 }
diff --git a/src/test/main.c b/src/test/main.c
index 73e5207..7b84bf6 100644
--- a/src/test/main.c
+++ b/src/test/main.c
@@ -259,6 +259,10 @@ int main()
   test(189, round(radians2degrees(convexPolygonSumInteriorAngles(3))) == 180);
   test(190, round(radians2degrees(regularPolygonInteriorAngle(3))) == 60);
   test(191, round(radians2degrees(convexPolygonExteriorAngle(3))) == 120);
+  test(192, arrangement(7, 0) == 1);
+  test(193, arrangementlf(7, 0) == 1);
+  test(194, roundTo(sideTriangleLC(5, 7, degrees2radians(179)), 5) == 11.99956);
+  test(195, roundTo(logarithm(1000, 10), 6) == 3);
 
   puts("Passed all tests successfully!");
 
diff --git a/src/trigonometry.h b/src/trigonometry.h
index a7558ef..badf8ed 100644
--- a/src/trigonometry.h
+++ b/src/trigonometry.h
@@ -45,7 +45,7 @@ double sideRightTriangle(double hypotenuse, double sideA)
 double sideTriangleLC(double sideA, double sideB, double oppositeAngle)
 {
   double result;
-  assert(sideA > 0 && sideB > 0 && oppositeAngle > 0);
+  assert(sideA > 0 && sideB > 0 && oppositeAngle > 0 && oppositeAngle < M_PI);
   result = sqrt(pow(sideA, 2) + pow(sideB, 2) - (2 * sideA * sideB * cos(oppositeAngle)));
   return result;
 }
@@ -61,7 +61,8 @@ double sideTriangleLC(double sideA, double sideB, double oppositeAngle)
 double angleTriangleLC(double oppositeSide, double sideA, double sideB)
 {
   double result;
-  assert(sideA > 0 && sideB > 0 && oppositeSide > 0);
+  assert(sideA > 0 && sideB > 0 && oppositeSide > 0 &&
+         oppositeSide < sideA + sideB && oppositeSide > fabs(sideA - sideB));
   result = acos((pow(sideA, 2) + pow(sideB, 2) - pow(oppositeSide, 2)) / (2 * sideA * sideB));
   return result;
 }
@@ -77,7 +78,8 @@ double angleTriangleLC(double oppositeSide, double sideA, double sideB)
 double sideTriangleLS(double oppositeAngle, double sideA, double oppositeAngle2A)
 {
   double result;
-  assert(sideA > 0 && oppositeAngle > 0 && oppositeAngle2A > 0);
+  assert(sideA > 0 && oppositeAngle > 0 && oppositeAngle < M_PI &&
+         oppositeAngle2A > 0 && oppositeAngle2A < M_PI);
   result = sideA / sin(oppositeAngle2A) * sin(oppositeAngle);
   return result;
 }
@@ -93,7 +95,8 @@ double sideTriangleLS(double oppositeAngle, double sideA, double oppositeAngle2A
 double angleTriangleLS(double oppositeSide, double sideA, double oppositeAngle2A)
 {
   double result;
-  assert(oppositeSide > 0 && sideA > 0 && oppositeAngle2A > 0);
+  assert(oppositeSide > 0 && sideA > 0 && oppositeAngle2A > 0 && oppositeAngle2A < M_PI &&
+         oppositeSide <= sideA / sin(oppositeAngle2A));
   result = asin(oppositeSide / (sideA / sin(oppositeAngle2A)));
   return result;
 }