#include <bits/stdc++.h>
using namespace std;
struct circle {
  long long x, y, r;
} C[100100];
long long X, Y, V, T, R;
int n;
const long double eps = 1e-8;
const long double pi = acos(-1.0);
int dcmp(long double x) {
  if (fabs(x) <= eps) return 0;
  return x < 0 ? -1 : 1;
}
vector<pair<long double, int> > ans;
int flag = 0;
void solve(circle c) {
  long double dis = sqrt((long double)(c.x - X) * (c.x - X) +
                         (long double)(c.y - Y) * (c.y - Y));
  if (dis <= c.r) {
    flag = 1;
    return;
  }
  if (dcmp(dis - c.r - R) >= 0) return;
  long double angO = atan2(c.y - Y, c.x - X);
  if (dcmp(angO) < 0) angO += 2 * pi;
  long double d = sqrt(dis * dis - c.r * c.r);
  long double ang;
  if (dcmp(R - d) >= 0) {
    ang = asin(c.r / dis);
  } else {
    ang = acos((R * R + dis * dis - c.r * c.r) / (2.0 * dis * R));
  }
  long double ang1 = angO - ang;
  long double ang2 = angO + ang;
  if (dcmp(ang1) < 0) {
    ang1 += 2.0 * pi;
    ans.push_back(make_pair(ang1, 1));
    ans.push_back(make_pair(2 * pi, -1));
    ans.push_back(make_pair(0.0, 1));
    ans.push_back(make_pair(ang2, -1));
  } else if (dcmp(ang2 - 2 * pi) > 0) {
    ang2 -= 2.0 * pi;
    ans.push_back(make_pair(ang1, 1));
    ans.push_back(make_pair(2 * pi, -1));
    ans.push_back(make_pair(0.0, 1));
    ans.push_back(make_pair(ang2, -1));
  } else {
    ans.push_back(make_pair(ang1, 1));
    ans.push_back(make_pair(ang2, -1));
  }
}
int main() {
  scanf("%I64d%I64d%I64d%I64d", &X, &Y, &V, &T);
  scanf("%d", &n);
  R = V * T;
  for (int i = 1; i <= n; i++) {
    scanf("%I64d%I64d%I64d", &C[i].x, &C[i].y, &C[i].r);
  }
  for (int i = 1; i <= n; i++) {
    solve(C[i]);
    if (flag) {
      printf("1.00000000000\n");
      return 0;
    }
  }
  sort(ans.begin(), ans.end());
  int now = 0, last = 0, tmp = 0;
  long double sum = 0.0;
  for (int i = 0; i < ans.size(); i++) {
    tmp += ans[i].second;
    now = i;
    if (tmp == 0) {
      sum += ans[now].first - ans[last].first;
      last = now + 1;
    }
  }
  cout << setprecision(11) << sum / (2.0 * pi) << endl;
  return 0;
}
