The measure of angle A to one decimal place is 71.8°
The value of angle A can be determined by using cosine rule. Cosine rule can be expressed mathematically ;
a² = b² + c² - 2bccosA
Since a = 10, b = 9 , c = 8
10² = 9² + 8² - 2 × 8 × 9 cosA
100 = 81 + 64 - 144coA
100 = 145 - 144cosA
144cosA = 100-145
cos A = -45/-144
cosA = 0.3125
A = 71.8° ( I decimal place)
Therefore, the value of angle A is 71.8°