
Mark H. answered 12/17/19
Experienced Tutor Specializing in Algebra, Geometry, and Calculus
Definition: Complimentary angles add up to 90°.
Let angle 1 and 2 be denoted as a1 and a2 respectively. The question states that a1 is 15 degrees (°) smaller than four (4) times a2.
To solve this problem, first write out the algebraic relations or formulas according to the statement and definition as follows:
(1) a1 (°) = (4*a2) - 15 ....or a1 -4a2 = -15
(2) a1 + a2 = 90°
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Now solve the system of equations by eliminating or canceling one of the constants (a1 or a2) to solve for the other constant.
By multiplying equation (2) by 4, you obtain
4a1 + 4a2 = 360°
Then by adding equation (1) and (2) yields
(4a1 + a1) + (4a2 - 4a2) = 360 + (-15).
Then by simplifying, we have the following expression
5a1 + 0a2 = 345 or a1 = 345/5 = 69 degrees.
Therefore, substituting in equation (2) yields
69 + a2 = 90 or a2 = 90 - 69 = 21 degrees
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Check:
(1) a1 = 4a2 -15 --> 69 = 4* 21 -15 = 84 -15 = 69✔