Trigonometric Ratios
A right triangle is defined as a triangle that has one interior angle with a measure of 90°.
The trigonometric ratios are defined as relationships between sides and angles on right triangles.
To better explain the required ratio, we'll include the following image that contains the given triangle, as described in the question:
The cosine of the angle T (shown in the figure) is defined as:
The secant of an angle is the reciprocal of the cosine, thus:
The adjacent side to angle T is 77 and the hypotenuse is 85, thus: