diff --git a/src/cat.ts b/src/cat.ts
index 46b91b0..c30edd3 100644
--- a/src/cat.ts
+++ b/src/cat.ts
@@ -242,6 +242,10 @@ export const Primitives: Environment<any> = {
     '%'(a, b) { return [(a as number) % (b as number)]; },
     'neg'(v) { return [-(v as number)]; },
 
+    'cos'(n) { return [Math.cos(n as number)]; },
+    'sin'(n) { return [Math.sin(n as number)]; },
+    'tan'(n) { return [Math.tan(n as number)]; },
+
     'to'() {
         const n_or_ns = this.nextToken('to', (v: any): v is (symbol | symbol[]) =>
             typeof v === 'symbol' || (Array.isArray(v) && v.every(w => typeof w === 'symbol')));