Answer:
x = 11.1
Its a right angle triangle with the values of its adjacent and hypotenuse given so cos is used.
im assuming the 4 is an exponent, so (2 * 3 * 7)^4 = 2^4 + 3^4 + 7^4 because of the distributive property. the ^4 gets distributed to everything inside of the parentheses.