diff --git a/src/reihen.c b/src/reihen.c
index 258638c..5fe2d8c 100644
--- a/src/reihen.c
+++ b/src/reihen.c
@@ -54,4 +54,24 @@ double pi(double eps){
         pi = (a + b) * (a + b) / (4 * t);
     } while (absD(pi - piold) > eps);
     return pi;
+}
+
+double sinD(double x){
+    if (x>=360.0){
+        x = squashDegreesTo360(x);
+    }
+    double sum = 0.0;
+    double currvalue;
+    x = radians(x);
+    double power;
+    unsigned long long faculty;
+    for (int i = 0; i <= 9; i++)
+    {
+        currvalue = 1.0;
+        currvalue *= powerD(2*i+1,x);
+        currvalue /= (double) fac(2*i+1);
+        if(i%2==0) sum += currvalue;
+        else sum -= currvalue;
+    }
+    return sum;
 }
\ No newline at end of file
diff --git a/src/reihen.h b/src/reihen.h
index 19f4b35..f056dfe 100644
--- a/src/reihen.h
+++ b/src/reihen.h
@@ -5,5 +5,6 @@ double exponential(double x);
 double euler();
 double pi();
 double radians(double d);
+double sinD(double d);
 
 #endif // reihen.h
\ No newline at end of file
diff --git a/test/test_reihen.c b/test/test_reihen.c
index 2a30593..a24ecb7 100644
--- a/test/test_reihen.c
+++ b/test/test_reihen.c
@@ -52,15 +52,24 @@ void test_degrees_to_radians(){
     r3 = radians(51.6);
     r4 = radians(36.97);
 
-    printf("%lf\n", r1);
-    printf("%lf\n", r2);
-    printf("%lf\n", r3);
-    printf("%lf\n", r4);
-
     TEST_ASSERT_DOUBLE_WITHIN(0.000001, 1.570796, r1);
     TEST_ASSERT_DOUBLE_WITHIN(0.000001, pi(1e-8), r2);
     TEST_ASSERT_DOUBLE_WITHIN(0.000001, 0.900589, r3);
     TEST_ASSERT_DOUBLE_WITHIN(0.000001, 0.645248, r4);
 }
 
+void test_sin(void){
+    double r1, r2, r3, r4;
+
+    r1 = sinD(50.0);
+    r2 = sinD(90.0);
+    r3 = sinD(36.97);
+    r4 = sinD(180.0);
+
+    TEST_ASSERT_DOUBLE_WITHIN(0.000001, 0.766044, r1);
+    TEST_ASSERT_DOUBLE_WITHIN(0.000001, 1.0, r2);
+    TEST_ASSERT_DOUBLE_WITHIN(0.000001, 0.601396, r3);
+    TEST_ASSERT_DOUBLE_WITHIN(0.000001, 0.0, r4);
+}
+
 #endif // TEST
\ No newline at end of file