-1 ≤ x² - x + 5/4 ≤ 1

-1 ≤ (x - 1/2)² + 1 ≤ 1

(x - 1/2)² + 1 ≥ 1

Check at x = 1/2

cosπx ≠ (x² - x + 5/4)

So

(x² - x + 5/4) > 1

No solution

x = √46 * 1/2 * 1/2 = √46/4

y = √46 * 1/2 * √3/2 = √138/4

z = √46 * √3/2 = √138/2

(x, y, z) = (√46/4, √138/4, √138/2)

Sol^n plz

(a + b + c)² = a² + b² + c² + 2(ab + bc + ca) ≥ 0

1 + 2(ab + bc + ca) ≥ 0

(ab + bc + ca) ≥ -1/2

-1 < -1/2

D

Solve

(10sin²@)sin²@+(15cos²@)cos²@=6

Compare with
Sin²@+cos²@=1

Sin²@=6/10=3/5
Cos²@=6/15=2/5

Cosec²@=5/3
Sec²@=5/2

Now

27*125/27 + 8*125/8=250

Radius of circle