Solution

src/figuresClasses.ts

@@ -1,11 +1,81 @@
-export interface Figure {}
+type ShapeType = 'triangle' | 'circle' | 'rectangle';
+type ColorType = 'red' | 'green' | 'blue';
 
-export class Triangle implements Figure {}
+export interface Figure {
+  shape: ShapeType;
+  color: ColorType;
+  getArea(): number;
+}
+
+export class Triangle implements Figure {
+  shape: ShapeType = 'triangle';
+
+  constructor(
+    public color: ColorType,
+    public a: number,
+    public b: number,
+    public c: number,
+  ) {
+    if (a <= 0 || b <= 0 || c <= 0) {
+      throw new Error('Sides must be greater than 0');
+    }
+
+    if (a >= b + c || b >= a + c || c >= a + b) {
+      throw new Error(`sides ${a}, ${b} and ${c} can't form a triangle`);
+    }
+  }
+
+  getArea(): number {
+    const p: number = (this.a + this.b + this.c) / 2;
+    const area: number = Math.sqrt(
+      p * (p - this.a) * (p - this.b) * (p - this.c),
+    );
+
+    return Math.floor(area * 100) / 100;
+  }
+}
+
+export class Circle implements Figure {
+  shape: ShapeType = 'circle';
 
-export class Circle implements Figure {}
+  constructor(
+    public color: ColorType,
+    public radius: number,
+  ) {
+    if (radius <= 0) {
+      throw new Error('Radius must be greater than 0');
+    }
+  }
+
+  getArea(): number {
+    const area: number = Math.PI * this.radius * this.radius;
+
+    return Math.floor(area * 100) / 100;
+  }
+}
+
+export class Rectangle implements Figure {
+  shape: ShapeType = 'rectangle';
+
+  constructor(
+    public color: ColorType,
+    public width: number,
+    public height: number,
+  ) {
+    if (width <= 0 || height <= 0) {
+      throw new Error('Width and height must be greater than 0');
+    }
+  }
+
+  getArea(): number {
+    const area: number = this.width * this.height;
+
+    return Math.floor(area * 100) / 100;
+  }
+}
 
-export class Rectangle implements Figure {}
+export function getInfo(figure: Figure): string {
+  const info: string = `${figure.color} ${figure.shape}`;
 
-export function getInfo(figure): string {
-  return typeof figure;
+  return `A ${info} - ${figure.getArea()}`;
 }