This study aimed at investigating the effect of a proposed strategy in Ist. Students achievement in solving problems in tringonometry unit. To addressed the strategy, The following was proposed : 1.Formulating problems in student's background. 2. Drawing up the strcture of the figure. Determining the following: Angle, hypotenus, opposite and law ( In the table ). Getting solution. Checking solution. Moreover, the study has tackled the following questions: What is the difference in students instant achievement between those who used the proposed strategy and those who did not? what is the difference in students late achievement between those who used the proposed strategy and those who did not? To answer such questions, the researcher chose an experimental group (N= 31) who was taught by the proposed strategy and a control group (N=31) who was taught by the traditional method. An achievement test then applied for both groups two times ; instantly after teaching and later on after a month to investigate the effect of the strategy in retaining students knowledge. T-test has used at (o: 0.05) and the following results: There is a significant difference between the control group and the experimental group in instant achievement concerning the teaching method in favor of the proposed strategy. There is a significant difference between the control group and the experimental group in late achievement concerning the teaching method in favor of the proposed strategy There is no significant difference between instant and late achievement of the experimental group students. Consequently, the researcher has drawn the following recommendation; necessity of well- planned and dear teaching stratigies in math books concerning teaching triangle problems. Teachers, may address and adapt these stratigies whilest teaching and adapt their students to use them effectively. Other studies, in the same area, are recommended to tackle such other stratigies and other studying stages