The phrase "announced his determination" is correct and usable in written English.
It can be used when someone is publicly stating their resolve or commitment to a particular course of action or goal.
Example: "During the meeting, he announced his determination to improve the company's performance in the upcoming quarter."
Alternatives: "declared his intent" or "expressed his resolve."
He announced his determination to run 365 miles in 2016, the equivalent of over 10 marathons.
It would be an occasion for grieving if Mr. Feinstein hadn't announced his determination to establish a new club somewhere in Midtown Manhattan.
But since then he has announced his determination to take greater control of monetary policy — and of the Central Bank — and has resisted calls for further interest rate hikes, even after the lira's dramatic fall on Friday.
Earlier this year he had a bad accident on an all-terrain vehicle and said that he might never be able to perform again, then quickly and heroically announced his determination to headline the eighth Ozzfest tour.
Scarcely had the United States declared war when Woodruff announced his determination to make Coke available, at a nickel a drink, to every member of our armed forces, no matter where he might be.
If anything, Labour's credibility deficit on the economy is even bigger in the spring of 2016 than it was a year ago, and it is against that backdrop that John McDonnell has announced his determination to exercise "iron discipline" over day-to-day government spending while being prepared to borrow for investment.
For a while, he goes along with April's bovarysme, halfheartedly tries to learn French, and even announces his determination to leave his job in the fall.
Maryland's governor, Martin O'Malley, chose Jan . 15 the birthday of Martin Luther King Jr., to announce his determination to repeal the state's law allowing capital punishment.
The most extreme eager beaver sleeps while playing motivational tapes, cites Elvis Presley and Engelbert Humperdinck as his role models and naïvely announces his determination to be a billionaire.
On the right, a fuming John Wilkes Booth Jeb Kreagerr) announces his determination to assassinate the president, orating in plummy theatrical tones about what he sees as Lincoln's betrayal of the country.
