Designate a theta angle

src/c/triangles.c

@@ -30,6 +30,10 @@ static void right_triangle_layer_update_proc(Layer *layer, GContext *ctx) {
 	graphics_draw_line(ctx, GPoint(start_x, base_y), GPoint(end_x, base_y));
 	graphics_draw_line(ctx, GPoint(start_x, base_y), GPoint(apex_x, apex_y));
 	graphics_draw_line(ctx, GPoint(end_x, base_y), GPoint(apex_x, apex_y));
+
+	// circle theta angle
+	graphics_context_set_stroke_color(ctx, GColorRed);
+	graphics_draw_circle(ctx, GPoint(tri->theta_angle_is_left ? start_x : end_x, base_y), 3);
 }
 
 RightTriangleLayer *right_triangle_layer_create(GRect frame, GColor color) {
@@ -41,9 +45,10 @@ RightTriangleLayer *right_triangle_layer_create(GRect frame, GColor color) {
 	tri->color = color;
 
 	// determine angles
-	tri->angle_A = 90;
-	tri->angle_B = rand() % 86;       // acute angle at left base vertex
+	tri->angle_A = 90;                // right angle at apex
+	tri->angle_B = 5 + rand() % 81;   // acute angle at left base vertex
 	tri->angle_C = 90 - tri->angle_B; // acute angle at right base vertex
+	tri->theta_angle_is_left = rand() % 2;
 
 	// choose hypotenuse length randomly
 	uint16_t min_hyp = (frame.size.w < frame.size.h) ? frame.size.w / 2 : frame.size.h / 2;