#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
const ld pi = 3.141592653589793238462l;
const ld ep = 1e-10;
int x[100005], y[100005];
struct pnt {
  ld x, y;
  pnt(ld x = 0, ld y = 0) : x(x), y(y) {}
  ld arg() { return atan2(y, x); }
  ld dist() { return hypot(x, y); }
} P, A[100005];
ll d2[100005];
int r[100005];
int sta[100005];
int n, v, T;
void answer(ld ans) {
  cout << fixed << setprecision(10) << ans << endl;
  exit(0);
}
using pdd = pair<ld, ld>;
vector<pdd> V;
int main() {
  scanf("%d %d", &x[0], &y[0]);
  scanf("%d %d", &v, &T);
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%d %d", &x[i], &y[i]);
    scanf("%d", &r[i]);
    x[i] -= x[0], y[i] -= y[0];
    A[i] = pnt(x[i], y[i]);
  }
  P = pnt(0, 0);
  for (int i = 1; i <= n; i++) {
    d2[i] = 1ll * x[i] * x[i] + 1ll * y[i] * y[i];
    if (d2[i] <= 1ll * r[i] * r[i]) answer(1);
  }
  if (v == 0) answer(0);
  if (T == 0) answer(0);
  ll v2 = 1ll * v * v;
  ll t2 = 1ll * T * T;
  pnt tmp[10];
  ld cur = -pi, ans = 0;
  ld rr = 1.0l * v * T;
  function<void(ld &)> fix = [](ld &al) {
    while (al < -pi) al += 2 * pi;
    while (al > pi) al -= 2 * pi;
  };
  for (int i = 1; i <= n; i++) {
    ll dd = d2[i] - 1ll * r[i] * r[i];
    ld L, R, al, be;
    al = A[i].arg();
    ld d = A[i].dist();
    if (dd / v2 <= t2)
      be = asin(r[i] / d);
    else if (d > rr + r[i] - ep)
      continue;
    else
      be = acos((rr * rr - 1ll * r[i] * r[i] + d2[i]) / 2 / d / rr);
    L = al - be, R = al + be;
    if (L < -pi) L += 2 * pi;
    if (R < -pi) R += 2 * pi;
    if (L > pi) L -= 2 * pi;
    if (R > pi) R -= 2 * pi;
    if (L > 0 && R < 0) {
      cur = max(cur, R);
      R += pi * 2;
    }
    if (abs(R - L) < 1e-10) continue;
    V.push_back(pdd(L, R));
    assert(R - L > -ep);
  }
  if (V.empty()) answer(0);
  sort(V.begin(), V.end());
  for (auto x : V) {
    if (x.first - cur > ep) ans += x.first - cur;
    cur = max(cur, x.second);
    if (cur > pi) break;
  }
  if (pi - cur > ep) ans += pi - cur;
  answer(1 - ans / pi / 2);
  return 0;
}
